Monday, 14 November 2011

Dead-spots revisited....

Ted Venema's excellent article on Cochlear dead-spots: of particular interest is the reverse sloping SN loss as in figure 5, which I've run into quite recently. It doesn't 'fit' into the normal models we are used to for gain - too much LF just masks out the better high frequencies, for what seems like not a lot of return in spatial awareness/loudness etc.

Identifying Cochlear Dead Spots

by Ted H. Venema, PhD
A primer on cochlear function as it relates to cochlear dead regions
How cochlear dead regions can be identified, what kinds of hearing losses are often associated with them, and why
Editor’s Note: This article1 and the interview that follows2 were originally published in the July/August 2003 (Vol 52, No 4) and March/April 2004 (vol 53, No 2) editions of The Hearing Professional, the official journal of The International Hearing Society (IHS). The articles are adapted and reprinted here with permission.
The cochlea is the “retina of the ear.” It changes sound into electrical impulses, and those impulses are the language the brain understands. Just as dead areas of the retina can create holes in one’s field of vision, dead hair cell areas of the cochlea can produce audiometrically useless frequencies. At these frequencies, hearing aid amplification does little or no good.
Brian Moore, PhD, a Cambridge University researcher in areas of psychoacoustics, has developed a protocol, called the Threshold Equalizing Noise (TEN) test, to clinically identify cochlear dead spots. The most interesting thing about this test is not its clinical utility and how well and consistently it identifies cochlear dead spots. Instead, the best thing about this test is that, in order to understand its rationale and how it works, one is forced to understand how the cochlea works.
Outer and Inner Hair Cell BasicsBy way of a brief overview, each cochlea contains one row of approximately 3,000 inner hair cells and 3-5 rows of about 12,000 outer hair cells (Figure 1).

Figure 1. The hairs or stereocilia of the outer hair cells are jammed into the underside of the tectorial membrane, while those of the inner hair cells are not. When soft sounds enter the cochlea, the test-tube shaped outer hair cells shrink, thus pulling the tectorial membrane down, so the stereocilia of the jug-shaped inner hair cells can be bent or sheared.
The jug-shaped inner hair cells send all sound information to the brain; without them we are totally deaf. These hair cells have one fundamental limitation, however: they cannot sense sounds softer than conversational speech.3 More specifically, the inner hair cells cannot sense signals below about 50 dB SPL for the low frequencies and below about 65 dB SPL for the high frequencies.4
The outer hair cells work in the opposite direction; that is, they receive messages from the brain and from within the cochlea telling them to rapidly stretch or shrink. These test-tube shaped outer hair cells are the active mechanism of the cochlea—the moving parts. Their movements help the inner hair cells sense soft sounds.
Sound hitting the eardrum results in a traveling wave of fluid motion inside the cochlea, thus causing a ripple along the floor upon which the hair cells stand (known as the basilar membrane). The stereocilia of the inner hair cells bend or become sheared where the wave peaks. This is what stimulates the hair cells at the cochlea’s wide base (high frequencies) or narrow apex (low frequencies) or at some unique place in between. In short, the wave grows (and slows) as it goes up the spiral-shaped cochlea until it reaches peak amplitude and stops. By the way, the main reason that the wave actually gets a peak in the first place is because it meets impedance along its travels up the spiral. As it is forced to slow down along its spiral route, its energy has to go somewhere; hence, its peak of “vertical” amplitude.
The wave’s peak is even further defined as a result of the action of the outer hair cells. The stretching/shrinking action of the outer hair cells temporarily alters the basilar membrane on either side of the peak. This mechanically forces the peak into a sharper point that, in turn, increases our ability to distinguish between frequencies that are close together. In someone with outer hair cell damage, the traveling wave peak is dull and rounded, and their ability to distinguish frequencies that are close together is diminished (Figure 2). Is it any wonder that those with sensorineural hearing loss (SNHL) and damaged outer hair cells have difficulty separating speech from background noise?

Figure 2. Without the action of the outer hair cells, the traveling wave has a dull and rounded peak. This passive traveling wave stimulates many adjacent frequencies simultaneously. The sharpening of the peak is accomplished with the action of the outer hair cells, and this increases the ability to distinguish between frequencies that are close together.
Why WDRC is Often RecommendedIt can safely be said, therefore, that the most common type of damage to the ear is damage to the outer hair cells. This results in the most common type of hearing loss: a moderate SNHL, where soft sounds below conversational speech (50–65 dB HL) are inaudible, yet 90-100 dB HL sounds are perceived as loud as they would be to someone with normal hearing. For this person, hearing aids should amplify the soft sounds significantly and amplify louder sounds by progressively smaller and smaller increments. Wide Dynamic Range Compression (WDRC) hearing aids that accomplish this are specifically intended to imitate what the outer hair cells once did. Outer hair cells begin their work for sounds below 50–65 dB SPL; hence, the knee-point of WDRC is most often found at input levels of around 50 dB, as well.

Figure 3. These idealized, schematic shapes represent three traveling wave envelopes. The top shows a normal traveling wave envelope, resulting from stimulation of two tones different in frequency. The middle shows a traveling wave envelope that is reduced in amplitude. Note also that the peaks are rounded, due to outer hair cell damage. The bottom shows what would happen with amplification. The original traveling wave size or amplitude is restored, but the peaks are still rounded. In other words, the ability to separate speech from background noise has not been restored.
It must be emphasized, however, that no matter how good a hearing aid is, it cannot restore a normal-functioning cochlear traveling wave (Figure 3). When the sharpened peak of a traveling wave becomes dull, it is dull for good. Hearing aids can only amplify and, by so doing, can only enlarge a diminished traveling wave. They cannot restore one’s original sharp frequency resolution or the ability to separate frequencies that are close together. Amplification only increases audibility of sounds, but does not come close to the majesty and wonder of the healthy cochlea.
Essential Cochlear ConceptsCochlear dead spots occur where there is complete destruction to both the inner and outer hair cells. As mentioned earlier, the gain provided by the outer hair cells to very soft input levels is about 50 dB for the low frequencies and about 65 dB for the high frequencies. Moore says that additional inner hair cell damage can only result in another 25-30 dB of hearing loss beyond 50 dB in the lows and 65 dB in the highs.4 This would make the maximum hearing loss possible from only hair cell damage about 75-80 dB in the lows and 95 dB in the highs.
An important fact to keep in mind is that the traveling wave is asymmetrical in shape (Figures 2-4). This concept is essential in understanding Moore’s test for cochlear dead spots. The traveling wave has a long tail towards the cochlea’s wide base (high-frequency region) and a steep front that is facing the cochlea’s low-frequency apex. This is our hearing physiology and explains “the upward spread of masking,” or that low frequencies mask high frequencies better than vice versa (Figure 4).

Figure 4. The traveling wave is asymmetrical in shape. Soft, high-frequency stimulation results in a small traveling wave at the base of the cochlea (right), which would easily be overcome or masked by the wave resulting from intense low-frequency stimulation at the apex (left). The reverse would not be true. Intense, high-frequency stimulation results in a traveling wave confined to the base of the cochlea (right) and, thus, it would not interfere with the wave resulting from soft low-frequency stimulation (left).
TEN Test ProceduresMoore’s TEN test for cochlear dead spots is available on a CD that can be played over a two-channel audiometer ( dead.html). The CD plays puretones, as well as a single broadband masking noise (noise that includes all audiometric frequencies). This broad-band noise is quite different from the narrow bands of noise used in our audiometers. The puretones and the masking noise have to be directed toward the same ear, and this can only be done with a two-channel audiometer. One can separately adjust the intensity of the tones and the masking noise by way of the intensity controls on the audiometer and send both to either the right or left ear. You begin by testing for thresholds of the puretones from the CD, and then testing the same ear for thresholds while the masking noise is presented into that ear (ie, ipsilateral masking).
When this article was first published in The Hearing Professional, the TEN test puretones and broadband masking noise were all calibrated in dB SPL, not HL. This is important to note when using the CD. If a client has normal hearing, the thresholds on the typical audiogram will look a bit like a barn roof (Figure 5), with best thresholds showing for the mid frequencies and borderline-to-mild hearing loss appearing for the low frequencies and high frequencies. The reason for this audiogram shape is that normal-hearing ears are most sensitive to frequencies between 1-4 kHz. Incidentally, this is why equalizer buttons on some stereo systems are shaped like a smile; we need the artificial boost for the lows and highs in order to hear all of the frequencies at equal loudness levels. To be sure, there are some complicated calibration issues that would need to be addressed in order to accurately translate the TEN test results to the typical audiogram with which we are all familiar. These, however, are beyond the scope of this introductory article. As of late last year, the TEN test5 is available in calibration of dB HL. This makes it easier to relate test results directly to the audiogram.
The procedure for Moore’s TEN is to first test for hearing thresholds for the puretones from the TEN CD in quiet, and then to retest for the same thresholds in the presence of ipsilateral masking. When using the test, be sure to go to a level whereby the better thresholds of the person are affected (ie, made worse by the masking). Compare the unmasked thresholds to the masked thresholds. The TEN should affect the better thresholds because it is audible to the person at these frequencies. The worst thresholds, however, should not be affected because the TEN should not be audible to the person at these frequencies. If they are, then suspect cochlear dead spots at these frequencies.

Figure 5. Moore’s TEN test on someone with normal hearing. Note that the thresholds from the puretones of the TEN CD produce a convex, “barn-roof” shape. This is due to the calibration of the CD tones in dB SPL, whereas the audiogram is measured in terms of dB hearing loss. Note also, however, that the thresholds masked by 30 dB TEN are only those thresholds that can hear it and not, for example, the worst threshold at 8000 Hz.
For a normal-hearing person, for example, 30 dB of the TEN from the CD should affect most thresholds (Figure 5). If the decibels on the audiogram were in dB SPL, all thresholds would be elevated or shifted to show a flat 30 dB hearing loss. On the typical audiogram (where dB HL rather than dB SPL is used), the barn-roof shaped thresholds for the normal-hearing person are still affected by the TEN. Figure 5 shows that, for any frequency where the broadband TEN is audible, thresholds within the TEN are shifted to at least the intensity of the TEN, so they are simply “pushed lower” down on the audiogram.
For someone with hearing loss, the main idea is to provide enough TEN masking so that the better thresholds are shifted, and determine if the worse thresholds are affected. For example, consider someone with a mild hearing loss for the low frequencies and a moderate hearing loss for the highs. The puretones played from the CD will show a similar trend; namely, better hearing for the low frequencies than for the high frequencies (Figure 6). Note that in the presence of ipsilaterally presented TEN, at 30 dB the thresholds for the puretones from the CD are tested again. A shift for the low-frequency thresholds appears, but this does not occur for the high-frequency thresholds. This only makes sense, because the person was not even able to hear the broadband TEN in the high frequencies.

Figure 6. The ipsilateral masking with 30 dB TEN affects the better low-to-mid frequency thresholds of the sloping SNHL, because the TEN is audible to the person at these frequencies. The TEN does not, however, affect the high-frequency thresholds because the TEN is not audible to the person at these frequencies. This would indicate a typical high-frequency SNHL that is due to damaged hair cells at these frequencies, but not due to high-frequency cochlear dead spots.
Similarly, according to Moore,4 if you masked the worst thresholds by their own minimum masking levels with the TEN, these thresholds should theoretically only be shifted to the level of the TEN used to mask them. Consider now that these worst thresholds are caused by cochlear dead spots: in this case, the minimum TEN level would actually shift the worst thresholds at least 10 dB beyond the decibel levels of the TEN itself. This is because these “worst” audiometric thresholds are not real; they are caused by cochlear dead spots and, thus, are actually far worse than the audiogram would suggest!
More “Suspicious” CasesOne type of SNHL that should give rise to suspicion of cochlear dead spots is a moderate degree of reverse hearing loss; another type is a severe degree of precipitous high-frequency hearing loss. For either type, amplification for the worst thresholds might not be the best course of action. For example, excess high-frequency gain can result in feedback for the person with precipitous hearing loss.
Moderate Reverse-Sloping SNHL. Be suspicious of reverse-sloping SNHL, as it could be indicative of low-frequency dead regions. It is very possible that the person could be completely deaf in the low frequencies; however, due to the asymmetric shape of the traveling wave, only a moderate reverse hearing loss may be revealed.
Consider someone who has completely dead inner and outer hair cells for the frequencies below 1000 Hz. In this case, intense low-frequency stimulation results in a traveling wave with a peak at the apical (low-frequency) hair cell region of the cochlea. The long tail of the traveling wave, however, may still extend into the healthy mid-frequency regions (Figure 7). Even though these low-frequency hair cells might be dead, a moderate amount of low-frequency stimulation might still excite living mid-frequency hair cells, thus causing the person to raise a hand, indicating he/she indeed heard a tone. In this case, the person might be “hearing” these low frequencies with their healthy mid-frequency hair cells, and not by means of their dead low-frequency hair cells!

Figure 7. Low-frequency dead spots may reveal only a moderate, low frequency SNHL with a reverse audiogram. Due to the long tail of the traveling wave, intense, low-frequency stimulation may “excite” the healthy mid-frequency hair cell regions (gray area of traveling wave diagram at top of figure). In this case, the person will indicate a response, but it will not truly arise from hearing in the low-frequency hair cell regions.
Severe Precipitous High-Frequency SNHL. Severe precipitous high-frequency SNHL can indicate high-frequency cochlear dead regions. Here, it is possible that the high-frequency thresholds do not truly arise from damaged high-frequency hair cells. On the contrary, these thresholds might result from indirect stimulation of low-frequency hair cells.
High-frequency stimulation would have to be quite intense to enable the steep front of the traveling wave to extend into the living, healthy mid-frequency hair cell regions. The steep slope of the precipitous high-frequency hearing loss thus might reflect the steep front of the traveling wave as it occurs in the cochlea(Figure 8). In this case, even though the high-frequency hair cells might be totally dead, an intense high-frequency tone might stimulate mid-frequency hair cells, causing the person to raise a hand indicating he/she heard something. The high-frequency thresholds are not truly indicative of high-frequency sensitivity; rather, they are a result of indirect stimulation of remote living hair cell regions.

Figure 8. High-frequency dead spots may reveal an audiogram showing a precipitous, pronounced degree of high-frequency SNHL. Due to the steep front of the traveling wave, intense, high-frequency stimulation may “excite” the healthy mid-frequency hair cell regions (gray area of traveling wave diagram at top of figure). In this case, the person will indicate a response, but it will not truly arise from high-frequency hair cell regions.
Reverse and Precipitous High-Frequency SNHLWith cochlear dead regions of hair cells, one actually hears by means of remote, living hair cells. This is called “off-frequency hearing.” A small amount of ipsilaterally presented broad-band TEN masking noise would elevate the normal (or better) thresholds in the living hair cell regions. In the reverse loss, it would make the good mid-to-high-frequency thresholds worse; in the precipitous high-frequency SNHL, it would make the good low-to-mid frequency thresholds worse. If the reverse or precipitous high-frequency hearing loss were due to cochlear dead spots, the TEN would, however, also elevate the thresholds for the worst thresholds, even though the TEN would theoretically be inaudible to the person at these frequencies!
Specifically, in the case of reverse SNHL, the ipsilaterally presented TEN would shift the low-frequency thresholds, even if these thresholds were greater than the intensity of the masking noise. In the case of the precipitous high-frequency SNHL, the TEN would also make the high-frequency thresholds worse, even if they were greater than the intensity of the masking noise.
Using conventional thinking, we would consider this impossible because, at these thresholds, the listener should not even be able to hear the masking noise. The reason why these thresholds are affected, however, is that, when one has dead hair cell regions at any frequency, one hears tones in these dead areas by means of a small piece of the traveling wave that extends into living hair cell regions. If the TEN masking noise does shift the worst thresholds by 10 dB or more, according to Moore, these thresholds are spurious, and do not actually arise from stimulation of damaged hair cells at these frequencies.4 Instead, in these cases, the worst thresholds arise from indirect stimulation of remote, living hair cells at other frequency regions. Therein lies the rub of Moore’s TEN test!
Of course, if the hair cells in question are only damaged and not truly dead, the same ipsilateral TEN masking noise would not shift these worst thresholds. In the case of the reverse SNHL, a small amount of TEN that was enough to shift the better mid-to-high-frequency thresholds would not affect the poorest thresholds at the low frequencies. In the case of the precipitous high-frequency SNHL, a small amount of TEN might indeed shift the good low-frequency thresholds, but would not affect the worst high-frequency thresholds by anywhere near 10 dB. These hearing losses would then, respectively, be a true reverse hearing loss and a true precipitous high-frequency hearing loss.
Figure 9 shows the thresholds for puretones from the TEN CD, followed by the thresholds found in the presence of 50 dB TEN from the CD. The ipsilateral TEN stimulation of 50 dB SPL should not have any effect on the high-frequency thresholds. In fact, the high-frequency thresholds are indeed affected because they show a shift of at least 10 dB. This finding, says Moore, would indicate cochlear dead spots for the high frequencies.4

Figure 9. The ipsilateral masking with 50 dB TEN affects the low-to-mid frequency thresholds of the sloping SNHL because the TEN is audible to the person at these frequencies. However, the TEN also shifts the high-frequency thresholds by at least 10 dB—even though it is not audible to the person at these frequencies. This would indicate a high-frequency SNHL that is due to high-frequency cochlear dead spots. The high-frequency thresholds thus do not truly arise from damaged high-frequency hair cells; rather, they are a result of stimulation of remote hair cells at the low-to-mid frequencies that are responding to intense high-frequency stimulation (ie, what Moore4 refers to as “off-frequency hearing”).
The implications for amplification are important here; namely, don’t focus on amplification in these extreme high-frequency thresholds. It might be best, in this case, to amplify the low-to-mid frequencies as well as the transition of the audiogram where the thresholds drop.
Summing Things UpIn ears with cochlear dead spots, tones are processed in the dead areas by means of living hair cells located on surrounding regions of the basilar membrane—what Moore refers to as “off-frequency hearing.” Some patients report that these tones do not sound natural or tonal in quality, or that puretone stimulation in these regions gives them the perception of a scratch or a tickle. These subjective reports, however, are not always consistent from person to person, even though dead areas might be indicated.4
The TEN test on the CD is not, in my opinion, a required part of any new test battery for our patients. On the other hand, the presence of reverse hearing loss or precipitous high-frequency hearing loss should make dispensing professionals suspicious that cochlear dead spots might exist. Furthermore, it is a good idea to ask these patients what their perceptions of audible tones presented to their worst thresholds are like. These two items—initial suspicions and secondary questions—might really help in our consideration of how much amplification to provide for a patient’s poorest thresholds. Should we provide low-frequency gain and output for reverse SNHL? For precipitous high-frequency SNHL, should we focus on amplifying the worst high-frequency thresholds or should we concentrate on amplifying the transition or steep slope itself?
Not to be forgotten, of course, is the education of ourselves; that is, understanding the TEN test for cochlear dead spots requires an appreciation for the fascinating way in which our cochleae function.

Monday, 7 November 2011

Monthly round up....(Late for October, but there you go).

Open week has pulled a few people out of the woodwork to try the Alera stock.

Positives: plenty of power and surprisingly good streamer performance.

Negatives: The power receiver design does not fit the power dome at all and the remote/bluetooth isn't as good as the Dex unit from Widex.

Lots of trials still happening so will report back as they come to a conclusion - people do seem to like the sound from the Alera range though  - which given the lack of performance from the Spice range is good. Spice+ however is just out and apparently deals with the glitches in the aids through the firmware update in Target 2. Unusual (100dB) 500hz resonances were seen by the REM machine on normal speech input, which I guess is a LF compensation built in to the prescription tool. I'm wondering if somebody got their sums wrong here as there was a peak even after the gain had been modelled through the feedback manager. The worst part was that the software didn't illustrate the level of power at all: it just looked like a flat 10-12dB gain but the output through the Avant showed more than 30dB of gain applied at the same point.

Right, more trials to sort.....

Thursday, 8 September 2011

My answer to the question of how hearing aids 'damage' your hearing through wear.....

Originally Posted by zafdor View Post
No, educate me.

Agreed on the conductive losses, I can understand that as an exception. since the conducted loss is in effect an attenuator to what the cochlea is exposed to. I don't see how compression/gain rules or the like would change the fact that a power aid can easily put out 130dB if you allow it to.

Perhaps a more insightful discussion is what exactly are the parameters of loud sounds that can cause permanent hearing loss. I personally take the somewhat ignorant and conservative approach that if I'm exposed to anything over 80db SPL c weighted average I wear hearing protection.
Originally Posted by MikeF View Post
I'll admit that my example indicates extreme hearing loss but even a typical person with 30-40 SPL DB amplification for some frequencies falls into the danger zone of having their hearing damaged during normal conversation, watching tv, or normal daily activities.

It is generally accepted that 90 DB sound levels for 8 hours a day and 100 DB sound levels for 2 hours per day can cause ear damage. Therefore people that had 30-40 SPL DB amplification would likely be in environments daily that could produce those sound levels.

If those levels of amplification could produce ear damage, you would think that an ENT or audiologist would warn people to stay away from vacuum cleaners, dishwashers, clothes dryers, air conditioners, walking in city streets, noisy restaurants, or even background music without ear protection or possibly removing the hearing aids. Also you would think that the ENT or audiologist would recommend that a person use headphones instead of hearing aids when watching tv since headphones do not over amplify deficient frequencies and it is likely that the person will hear the tv better than with hearing aids.

So it appears that amplification for someone that doesn't hear certain sounds has a different effect on the possibility of damage to ears than over amplification of sounds for people with normal hearing. It would be nice to get some hard facts about hearing aids and ear damage instead of just speculation (lot of speculation on the Internet) so that each of us can try to create an environment that enhances our lives. I have yet to see an ENT indicate that properly adjusted hearing aids will either cause or not cause ear damage.
OK, it comes down to the application of gain.

First you have to understand that these numbers we throw around on here 80-90-100 dB aren't a linear scale. To put it simply, if one speaker puts out 80dB and you put another speaker right next to it you produce a whopping 83dB. So a doubling of 'power' equates to a 3dB rise in measured output.

The next thing to take into the equation is that there's a reasonability test applied to gain which forms the basis of all gain calculations. IE: how much sound is 'needed' to hear whilst staying within people's UCL or uncomfortable loudness levels.

The third aspect is that the inputs we have been discussing (speech) aren't 65dB AVERAGE, they are 65 dB 'peak' value. The average value is about 30-40dB depending on the mix of ambient and speech proportion.

The fourth part of this is that given all of the above, engineers determined in the 50's 60's 70's 80's and 90's refinements to the basic concepts so that you don't break some fairly fundamental 'rules' of gain.

Namely: 1/2 gain and 1/3 gain rules, basically that if you have a conductive hearing loss, you will receive Half that amount back in gain, at the appropriate frequencies. If you have sensorineural loss, that will be 1/3 or less. Now in our fancy digital age, there are systems that deviate from this to an extent, but that's the basic precept.

So, if you have a 60dB loss, on average, you'll get 20dB gain on average. Which, even on a 65dB input signal doesn't put you anywhere near the 85dB (Aleq), simply because the average dose of continuous speech at 85dB is going to be around 40-50dB. Any more than this is going to do your swede in as you'll get Auditory Fatigue from the long term exposure.

To combat this, for the last couple of decades hearing aids have been built with circuits that incorporate compression - compression is a technique which allows louder sounds to be given less gain while still amplifying the quieter ones. This has the beneficial effect of making the quieter sounds audible but not blowing your head off with the louder sounds. Now, you'll hear some people saying that compression is bad, and linearity is good, especially for music. Yes, this is true to an extent, but, non-believers, listen-up! you've had some degree of compression in your analogue aids for years - go and dig out the old Gennum and K-Amp specs if you like - or even ask Mead Killion (if he's still going around on his unicycle....) Basically all circuits compress the output to some extent to avoid the receiver clipping - overdrive distortion on the sound. ~(output-limiting compression)

And finally, just when you think that the manufacturers are really going to do you down, we have software. All the stuff you can see, and all the stuff you cant. Here's a though: wouldn't it be a really good idea to put a limiter into ALL hearing aids? Just to keep the Lawyers happy and to stop self-programmers from really doing damage? Well, what if we put in default UCL limiters at 105-110dB? So that the peak values of the output wouldn't do any real harm......You can override them of course, but that's at your risk.

Just think, if somebody fires a gun near your head with occluding hearing aids in - you'll experience less hearing damage than the person who fired it.....

So, there it is, in a nutshell. Hearing aids listening to speech are unlikely to damage your hearing further. I hope that doesn't sound to patronising. If you want more info, try to get hold of the excellent book: Hearing Aid by Harvey Dillon or Andi VonLanthen's one.

Thursday, 1 September 2011

Reverse Slope Hearing loss - Good article and explanation from a patient.

The Bizarre World of Extreme Reverse-Slope
(or Low Frequency) Hearing Loss
(short, abridged version)

(Click here to read the complete, unabridged version)
© April 2007 (latest revision August 2007), by Neil Bauman, Ph.D.
Table of Contents
Imagine a person with a hearing loss so severe he can’t hear thunder rumbling overhead, yet, at the same time, he has hearing so acute he can hear a pin drop; or imagine a person that can’t hear you talking just 4 feet away, yet clearly hears a whisper from across a large room; or imagine a person that can’t hear a car motor running right beside him, yet can hear a single dry leaf skittering along in the gutter 50 feet away.
“Impossible,” you say, “a person could never have such good and bad hearing at the same time!”
Surprise! It’s true. Welcome to my world—the bizarre world of people with extreme reverse-slope hearing losses.

What Is Reverse-Slope (or Low Frequency) Hearing Loss?

Hearing losses are sometimes classified according to the shape they form on an audiogram. They commonly go by strange names such as ski-slope loss, cookie-bite loss, flat loss, reverse cookie-bite loss and reverse-slope (or reverse curve) hearing loss. (My article Kinds of Hearing Losses explains these different hearing losses and illustrates the various shapes they form on audiograms.)
   Fig. 1.  Severe ski-slope
By far the most common kind of hearing loss is the typical ski-slope loss where the line on the audiogram slopes down to the right (Fig. 1). In contrast, a reverse-slope loss (as its name implies) does the reverse and slopes upto the right (Fig. 2).
   Fig. 2. Severe reverse-slope
As a result, this kind of hearing loss is sometimes referred to as an up-sloping loss, a rising loss, or  low-frequency hearing loss, but by far the most common name is the reverse-slope (or reverse-curve) hearing loss.
   Fig. 3.  Mild reverse-slope
Don’t make the mistake of thinking that all reverse-slope losses are the same. Nothing could be further from the truth. There is an enormous difference in hearing between a mild, gently-sloping reverse-slope hearing loss (Fig. 3), and a severe or profound steeply-sloping reverse-slope loss (Fig. 4), just as there is between the various degrees of ski-slope hearing losses.
For practical purposes, we can group reverse-slope hearing losses into three basic classes.

  Fig. 4.  Neil's severe reverse-slope loss
               at age 21
Class 1.     The most common form of this relatively-rare loss is a gently up-sloping line in the standard audiometric frequencies between 250 and 8,000 Hz (Fig. 3). In this class, the worst low-frequency hearing loss typically lies somewhere between mild and moderately-severe. Class 1 curves are often seen in the beginning stages of Meniere’s disease.
Class 2.     Rarer, is a fairly-steep up-sloping line in the standard audiometric frequencies. In this class, there is a moderate to severe hearing loss in the frequencies below 1,000 Hz, but at the same time, hearing becomes virtually normal somewhere in the range of 2,000 to 6,000 Hz (Fig. 2). It is in Class 2 that the differences between reverse-slope losses and ski-slope losses really become apparent.
Class 3.     The rarest form of the reverse-slope loss reveals a steep up-sloping line ranging from severe to profound hearing loss (70 to 110 dB) in the low frequencies to incredible hearing in the very high frequencies (those frequencies above 8,000 Hz) (Fig. 4).
Years ago (when I was in my early 20s) my hearing ranged from 75 dB at 1,000 Hz to -30 dB in the frequencies above 16,000 Hz (Fig. 4). (Note: numbers above the 0 dB line represent super-acute hearing, and are expressed as negative numbers.) Since I could easily hear “silent” dog whistles, some said I had “dog ears” hearing.
It is here in Class 3, with its incredible range of over 100 dB between the faintest low-frequency sound heard and the faintest high-frequency sound heard, that truly bizarre hearing is the most pronounced. Since my hearing loss spanned an incredible range of 105 dB, no wonder people were always confused about what I could, and could not, hear!
For example, my former mother-in-law wouldn’t believe my hearing was as bad as it was because she would whisper when she didn’t want me to hear something, and I would easily hear her. (She never caught on that if she just spoke in a normal voice, I wouldn’t have understood a thing!) (Back to Table of Contents)

How Common Are Reverse-Slope (or Low Frequency) Hearing Losses?

Mild reverse-slope hearing losses are relatively rare. However, extreme reverse-slope hearing losses like mine are much rarer still. Dr. Charles Berlin, formerly head of the Kresge Institute in Louisiana, one researcher that has studied this kind of hearing loss fairly extensively, estimates that out of the roughly 31 million hard of hearing people in the USA, there are 3,000 plus people that have my unusual kind of reverse-slope hearing loss. (Back to Table of Contents)

Causes of Reverse-Slope (or Low Frequency) Hearing Losses

When people think of causes of reverse-slope losses, typically they think about Meniere’s disease. Classic Meniere’s disease does indeed often, but not always, result in a reverse-slope hearing loss (Class 1 curve), at least in the beginning stages.
However, probably the most common cause of reverse-slope hearing losses, particularly in Classes 2 and 3, is of genetic origin. Hereditary losses often seem to run in our families.
Reverse-slope hearing loss has run in my family for the past four generations. Those that I know of include my maternal grandfather, my mother, myself, my brother, my younger daughter and my brother’s older son. I know of a number of other people who also have reverse-slope hearing losses running in their families—some also for the past 4 or 5 generations.
It appears that extreme reverse-slope hearing losses are a dominant genetic trait. It certainly is in my family. Each person born in my family has a 50% chance of having this kind of hearing loss.
Another interesting characteristic of severe or extreme reverse-slope hearing losses such as mine is that they seem to be non-syndromic—that is, they don’t have any other conditions or syndromes associated with them.
In addition to Meniere’s disease and genetic mutations, various childhood diseases are thought to occasionally result in reverse-slope hearing losses. As Judith explained, “My hearing loss apparently was the result of measles at the age of 2.” Debbie’s daughter “was not born with a hearing loss, but acquired it from complications of chicken pox” also at age 2. (Back to Table of Contents)

How Reverse-Slope (or Low Frequency) Hearing Losses Progress

Whether reverse-slope losses get worse with time depends on what caused the loss in the first place. (Back to Table of Contents)

Meniere’s Disease

One of the characteristics of Meniere’s disease is that it typically results in a progressive, fluctuating, step-wise hearing loss. Thus if you have Meniere’s disease, initially you may have a Class 1 type of reverse-slope loss. Over time, as your Meniere’s Disease progresses, you will likely find that this reverse-slope loss slowly evolves into a reverse cookie-bite or flat loss, and ultimately into some degree of a severe or profound ski-slope loss. (Back to Table of Contents)

Hereditary losses

With hereditary reverse-slope losses, we seem to go through three distinct stages.
Stage 1: The first stage occurs from birth to around 5 years of age. It appears that although there is some degree of hearing loss at birth, hearing in the lower frequencies rapidly decreases until around age 5 or so.
Furthermore, it seems that because of our excellent high-frequency hearing, and because of our excellent speechreading skills at a very early age (of which our parents are typically totally unaware), our hearing losses do not become apparent until something happens to drive home the fact that we cannot hear well.
For example, my parents didn’t discover I had a hearing loss until I was about 4 or 5. One day my dad, who was standing behind me where I couldn’t speechread him, asked, “Do you want to come for a ride in the car with me?” I totally ignored him, and continued playing on the floor. He knew something was wrong because I loved riding in the car! (It was a ‘29 Buick back in those days.) Another time he asked me if I wanted some ice cream—which I still love—and again I ignored him. It was at this point that my parents had my hearing tested and discovered I had a severe hearing loss!
Stage 2: The second stage begins around age 5 and continues without significant change to around age 50 (if there are no other factors involved such as hearing loss from noise damage, or from taking ototoxic drugs, for example). Thus, once we learn to adapt to our strange hearing losses, our coping strategies can remain the same for most of our lives.
   Fig. 5.  Average  (ski-slope) hearing loss
                curves with increasing age
Stage 3: The third stage kicks in about age 50 and continues for the rest of our lives. This is not really our reverse-slope hearing loss progressing, but rather, the effects of aging dramatically impinging on our precious high-frequency hearing. Here’s what happens.
As people age, they typically begin to lose their high-frequency hearing. This happens slowly and insidiously over many years. Fig. 5 plots “average” curves showing increasing high-frequency hearing loss from ages 40 (top line) to age 80 (bottom line).
Notice that people with the typical ski-slope losses have already lost their high-frequency hearing (but retain their low-frequency hearing). Thus as they age, they don’t have much high-frequency hearing left to lose.
   Fig. 6.  Progression of Neil's reverse-
                slope loss at age 59
In contrast, those of us with extreme reverse-slope losses have most of our residual hearing in the high (and very high) frequencies, yet it is these very frequencies that people typically lose as they get older. As a result, somewhere around age 50 or so we begin to notice a significant drop in our hearing. Our reverse-slope losses rapidly begin to flatten, and in time become more or less “flat” curves.
For example, between ages 50 and 60, I lost much of my excellent high-frequency hearing. You can verify this by comparing my audiogram taken at around age 21 (Fig. 4) with my current audiogram (Fig. 6) taken at age 59.  As you can see, I have lost much of my high-frequency hearing. (In fact, I am following the same hearing loss pattern my mother went though as she aged.) (Back to Table of Contents)

The Blessing of Perfect Speech

One of the things that surprises many people is that all of us with severe reverse-slope losses have perfectly-normal or near-normal speech. Imagine a person that is essentially deaf, yet has flawless enunciation, perfectly-formed and well-modulated speech, all without having had any speech therapy. This is one of the blessings of having a severe reverse-slope hearing loss.
Shirley explains, “Because I have high-frequency hearing, my voice has never been affected by my hearing loss, although my hearing loss is profound.”
It’s the same with me. Because my speech is also indistinguishable from the speech of people with normal hearing, I’ve had many people refuse to believe how bad my hearing really is. Peggy, herself hard of hearing, after hearing me speak, exclaimed, “Do you realize that your speech is absolutely perfect? You must have worked very hard to perfect your tone like that, what with growing up hard of hearing.” The truth is, I’ve never had speech therapy. I’ve never needed it.
The real secret to perfectly-normal speech is hearing all speech frequencies, especially the high-frequency consonants such as “s,” “f,” “sh,” “ch,” “t,” and “th.”
When you can’t hear these sounds, it is very difficult to produce them properly. In fact, I can tell if a person has a profound loss just by the way they move their lips when they try to produce these sounds. Think how difficult, or impossible, it would be to learn to whistle if you couldn’t hear any of the sounds you were trying to produce. In like manner, correctly producing the above voiceless sounds depends so much on aural feedback—meaning you listen to the sound you make, and if it isn’t “right on” you immediately correct it. If you cannot hear it, you don’t get this feedback so you don’t correct these sounds, and your poor speech reflects this.
Since those of us with severe reverse-slope losses hear these “voiceless” sounds the best, we use them correctly in our speech, and thus avoid the flat “deaf speech” patterns of many of those with severe ski-slope losses. (Back to Table of Contents)

What It’s Like to Live with a Reverse-Slope (or Low Frequency) Hearing Loss

Having a Class 2 or 3 reverse-slope loss makes for some interesting experiences. Here are a few of the more bizarre things we hear, or don’t hear, and how we cope with it.
  • We don’t hear appliances running. Thus we have to put our hands on household appliances (fridge, washer, drier, furnace, etc) and feel the vibrations in order to know if they are running. However, we can readily hear the faint click of the relays from across a room as they kick in or out to start/stop these appliances, but we don’t know whether they just started or just stopped.
  • We hear whispers very clearly—even from across a room. In school, I used to hear kids whispering from across the classroom, yet couldn't hear the teacher talking only a few feet away. It always puzzled me that the teachers never heard all the whispering that to me was so loud. Since whispering seemed so loud to me, when I used to “whisper,” I’d actually use “low voice” (which to me sounded very faint as compared to whispering). To my chagrin, everyone around heard me “whispering.” My wife kept telling me to “whisper.” It eventually dawned on me that others couldn’t hear the whispers I so easily heard.
  • Since I can’t hear my car’s motor running, sometimes when I am parked I may try to start my car a second time thinking it hadn’t started. The suddenly-swiveled heads of the people nearby tell me that I just ground the gears on the starter—again! Now, I always look at the tachometer first. If it’s not reading 0, I leave the starter alone!
  • The screech of the wheels of trains on the tracks is so loud to me that it hurts my ears—yet to most people this is not even a loud sound. Imagine not being able to hear the loud roar of a train bearing down on you, yet getting headaches from the painfully-loud screech (to me) of the train wheels against the tracks as the train goes around a curve.
  • We can easily hear high-frequency sounds most people can’t hear. For example, I could easily hear the faint 15,734 Hz whine produced by the fly-back transformer of a TV from anywhere in the house, and even fromoutside the house, yet I had to put my ear about 6 inches from the TV’s speaker in order to understand any speech from it (if the volume was set to normal hearing levels).
  • To me, certain insects chirping from a block away (even just one insect) produce a racket loud enough to drown out the voice of a person standing almost nose-to-nose speaking. The “funny” thing (to me) is that people with normal hearing either can’t hear that insect at all, or only hear it very faintly!
  • We hear some birds singing and chirping away, but not others. For example, I have never heard the low-frequency sounds of an owl hooting or a Mourning Dove cooing (although I have a flock of Mourning Doves right outside my back door), yet I can easily hear a male hummingbird’s high-pitched angry squeaks as it chases off a competitor, or the wonderful trilling sounds it makes as it power dives to impress its prospective mate.
  • Although we have severe hearing losses in the speech frequencies, we can easily hear faint high-frequency sounds such as a pin dropping on a table or hard floor. Sarah explains, “I have a 60-80 dB reverse-slope hearing loss. I can hear a pin drop, but normally can’t hear thunder!” (Back to Table of Contents)

Practical Differences Between Reverse-Slope and Ski-Slope Losses

Although there are many coping skills that are common to all kinds of hearing losses, a number of the coping skills you typically read about were designed with the needs of people with ski-slope losses in mind. They were not designed for those of us with reverse-slope losses—yet people think we need these coping strategies, but we often need the opposite. Here are three examples.
1.     People with ski-slope losses don’t want you to speak louder, but clearer.
One of the “rules” when speaking to a hard of hearing person (really meaning those with ski-slope losses) is that you don’t “yell” at them, but speak slowly and clearly at your normal volume. This approach is totally wrong for those of us with reverse-slope losses. We need people to speak louder in order to hear speech in the first place.
If you have a ski-slope loss you hear the loud vowel sounds, but not the soft consonants. Thus you hear people talking with no problem, but because most of the intelligence of speech is in the consonants, you don’t understand what people are saying. To you, speech sounds muffled because you don’t hear the high-frequency sounds. Thus you primarily want more clarity, not more volume.
In contrast, those of us with reverse-slope losses hear the soft, high-frequency consonant sounds. To us, speech is thin, almost inaudible and often sounds like whispers. For example, as I approach someone talking, the first sounds I hear are the high-frequency voiceless “s” sounds. We do not really hear a person talking until we get very close so we can hear the “voiced sounds.” Thus we typically need more volume.
2.     People with ski-slope losses hear men better than women.
“Common wisdom” says that hard of hearing people hear men better than women and children. This is true for people with the typical ski-slope losses because they hear the louder, lower-pitched voices of men better. Women and children with their higher-pitched (and often softer) voices are much more difficult for them to hear and understand.
This “wisdom” is again totally wrong for those of us with reverse-slope losses. Since we hear the higher-frequency sounds best, we typically hear women’s voices better than men’s voices. I much prefer talking to women as their higher-pitched voices are more in tune with my ears. If men speak in a high falsetto voice I then hear them well too. It might sound ridiculous, but it works!
3.     If you have a ski-slope loss, low-frequency noise drowns out speech.
Loud low-frequency noise is the bane of people with ski-slope losses. Speech is lost in the racket caused by the noise in factories and mills, and by the air conditioning/heating fans in our homes, offices and schools, thus people with ski-slope losses have to shout over all the low-frequency noise around them. Since we don’t hear low-frequency sounds well, we clearly hear the people shouting. That’s one situation where I tell people (tongue in cheek), “You don’t have to yell at me. I’m not deaf!” By the same token, we often do not raise our voices enough in such situations so people with normal hearing can hear us talking over the low-frequency racket.
In contrast, we cannot hear speech through all the high-frequency sounds around us. The bane of our lives are nearby sounds such as running water, clinking cutlery, rustling and crumpling papers and people whispering. (Back to Table of Contents)

Wednesday, 24 August 2011

Nice to see Speccies and Action On Hearing Loss (RNID) in bed together...

UK sitting on hearing loss time bomb

Posted on 21/06/2011
One in three people with hearing difficulties is too embarrassed to wear a hearing aid and refuse to visit an audiologist for advice, according to a recent study by Specsavers Hearing Centres. Of those polled only 16% sought help immediately after recognising a loss of hearing.

Specsavers hopes to change attitudes to hearing loss by forging a strategic partnership with the UK largest charity for the deaf and hard of hearing – Action on Hearing Loss (formerly RNID).

Action on Hearing Loss, which this year celebrates its centenary, has signed a five year agreement with Specsavers Hearing Centres to work together to remove the stigma of hearing loss and promote hearing health. Together they have pledged to reach one million people nationwide over the next year by offering free hearing checks in-store and online.

According to the charity's report, Hearing Matters, it is estimated that up to four million people in the UK would benefit from a hearing aid and that this figure will rise as our population ages and noise pollution increases. By 2031 it is predicted that 14.5 million people in the UK will have some form of hearing loss.

Action on Hearing Loss chief executive, Jackie Ballard says: 'Our own research shows that 45% of people who reported hearing problems to their GP were, at first not referred for a hearing test, and that there is, on average, a ten year delay between symptoms and treatment. We are calling on the government to commit to a national strategy for dealing with hearing loss and to prioritise it in line with other major health issues, such as dementia.'

Jackie Ballard continues: 'Prevention and early diagnosis can significantly reduce the impact of hearing loss, which can lead to social isolation and increased mental health problems impacting the NHS. By introducing an adult screening programme, the government could save the country an estimated £2 billion.'

Specsavers Hearing Centres marketing director Mathew Gully, welcomes the news: ‘We are really delighted to be working with the nation’s largest charity taking action on hearing loss. This partnership marks the start of a new chapter in the way the nation views and treats hearing loss. Hearing is fundamental to an individual’s quality of life, as well as those around them.

'We shall be working together to normalise hearing loss, much as Specsavers has done with vision, offering people the best solution and promoting easy access to hearing care. After all, there is no logical reason why there should be any difference in the way we think of vision and hearing. If together we can change people’s attitudes to wearing hearing aids, as we have with the wearing of glasses, then we will have achieved our goal.’

Jackie Ballard adds: 'It is really important to us that whoever we work with has a good reputation and shares our ambition to reach those four million people who would benefit from wearing a hearing aid. We believe that Specsavers can bring their marketing expertise and ability to reach a wide audience to help us remove the stigma surrounding this issue.

'Poor communication is the most serious barrier for people with hearing loss and can have significant personal and social costs, leading to social isolation and mental health issues. People don't think twice now about having their eyesight checked regularly but they put off having their hearing tested. Anything we can do to remove the stigma and encourage people to take action and seek help as soon as possible will have a huge impact.’'

For general media enquiries:

Rohini Simbodyal, PR Officer, telephone: 020 7296 8274 or

Notes to editors:

  1. Specsavers is the largest retail dispenser of digital hearing aids in the UK, offering a hearing service from more than 400 locations.
  2. Specsavers Sound Check the Nation survey of 825 UK residents carried out between 15 March 2011 and 09 April 2011 across all UK regions
  3. Action on Hearing Loss is the charity working for a world where hearing loss doesn't limit or label people, where tinnitus is silenced – and where people value and look after their hearing.
  4. Highlights of Action on Hearing Loss' Hearing Matters Report include:
    a) By 2030, the World Health Organisation would rank hearing loss in the top 10 disease burdens in high- and middle-income countries.
    b) Significant underinvestment in hearing research and a lack of progress in translating scientific discoveries into commercial treatments are holding us back. In 2010, The UK spent £1.34 on research into hearing loss for every person affected. This compares to £14.21 for sight loss, £21.31 for diabetes, and £49.71 for cardiovascular research.
    c) It takes, on average, 10 years for people from recognising a hearing loss to taking action. It’s important that people take action quickly because they can benefit from hearing aids sooner and be less likely to experience unnecessary isolation, which can lead to depression. The Action on Hearing Loss hearing check is an easy way for people to take the first steps to addressing their hearing loss.
    d) There are currently four million people in the UK who would benefit from wearing a hearing aid, but have yet to do anything about it. Action on Hearing Loss wants to remove the barriers to treatment, and the stigma of hearing loss, to enable these people to take action and live their lives to the full.
    A further four million young people in the UK are at risk of avoidable hearing damage from amplified music, but the government and educators are failing to recognise the magnitude of the issue.
    Referral of adults with hearing loss to sensory, social care and other rehabilitation services is ad hoc and sometimes completely lacking. Key services and support such as lipreading classes are also at risk of decline.

Thursday, 11 August 2011

Excellent rehabilitation Article Written in 2004.

This article provides some excellent ideas for dealing with patients and their experiences of hearing aid wear.

Becoming Friends with Your New Hearing Aids

© May 2004 by Neil Bauman, Ph.D.
Question: My audiologist did not adequately prepare me for the challenges I would face in adjusting to wearing my new hearing aids. What is the best way to adapt to wearing hearing aids?—V. O.
Answer: Good question. Let's go right back to the beginning. Far too often, people have unrealistic expectations as they anticipate hearing again with their new hearing aids. For many people, the scenario goes something like this.
The big day arrives. You are excited. You should be. Today you are going to hear again! Today you will receive brand new hearing aids.
Your audiologist carefully fits and adjusts them to meet your special hearing needs. She tests you with them to be sure you hear as well as possible. You are thrilled to hear her voice so clearly with your new aids.
You proudly walk out of her office. You are now on your own with your new "ears." You look forward to a hearing adventure.
You leave the building and step out into the street. Suddenly a horrible cacophony of sounds assaults your ears. You are shocked right out of your socks! You don't ever remember traffic being this noisy. You can't stand the awful racket. Quickly you reach up and yank your hearing aids out of your ears and stuff them into your pocket—and your dream of hearing again is shattered.

Please Don't Dump Me in Your Drawer

If this has been your experience, you are certainly not alone. Close to 200,000 hard of hearing people in the UK have done the same. In fact, one in every six to eight hearing aids sold today soon lie neglected and forgotten in dresser drawers.
To the above, add the enormous numbers of hard of hearing people who only drag their hearing aids out for certain special occasions. The rest of the time their hearing aids also languish in pockets and purses or get dumped back into dresser drawers.
This is a tragedy. Hearing aids designed to live in people's ears too often are denied the opportunity to help their owners hear better. Why do people pay good money—up to £3,000.00 for each hearing aid—and then not wear them? Even more to the point, what should people be doing so that they will become successful users of hearing aids? Here are some answers.

Have Realistic Expectations of What Your Hearing Aids Will Do for You

Before you are even fitted for new hearing aids, you need to have realistic expectations of what hearing aids will and will not do for you.

1. Hearing Aids Will Not Give You Normal Hearing

Hearing aids are aids to better hearing. They are not cures for hearing loss. Hearing aids will typically reduce your hearing loss to about half of what it was before. This means that for those of us with significant hearing losses, at best, we will still have mild to moderate hearing losses. Thus, if you expect normal hearing, you will be sadly disappointed. However, if you expect to hear better, you will be pleased with your new hearing aids—particularly in quiet situations.
If you set your expectations too high, you may be so disillusioned that you may toss your hearing aids in some dresser drawer and forget about them.
For example, one elderly lady was fitted with hearing aids that allowed her to hear and understand about 95% of what people were saying. After 4 weeks, she returned the hearing aids to her audiologist and asked for a refund. Why? Because she was upset that she was still missing 5%!
She consigned herself to a life of frustration and silence, because she focused on the 5% she missed rather than on the whopping 95% she now could hear.

2. It Takes Time to Adjust to Wearing Hearing Aids

It comes as a shock to many people that they need time to adjust to wearing hearing aids. They think that adjusting to wearing new hearing aids should be like putting on new glasses—instant clear sight.
The truth is, you need to give your brain time to relearn how to hear and process all the new sounds it is now hearing—especially if your hearing loss was gradual. You gradually lost certain sounds. Now, when you put on hearing aids, all of a sudden these sounds blast your ears and you are overwhelmed.
It takes time for you to get reacquainted with the sounds you haven't heard well for decades. This does not happen in a day or even a week. Your brain needs from 30 to 90 days or even longer to complete this process—so if you give up before this time, you will think hearing aids don't work for you and you could be very wrong.

3. Everything Is Too Loud Now

One of the biggest shocks people experience when wearing new hearing aids is how loud everyday sounds now seem. The toilet flushing thunders like Niagara Falls! Clinking cutlery sounds like jackhammers. Initially, you may find you cannot stand rustling papers, running water and other everyday sounds.
However, with time, your brain will learn to turn down its internal volume control so these sounds become bearable. This is another reason you need to persevere during those first 90 days. Unfortunately, many people give up before this happens. If they had kept using their hearing aids a little longer, they would have succeeded.
People with sensorineural hearing losses also often suffer from recruitment. Recruitment is the perception that sounds increase in volume faster than they really do. Thus, if you ask a person to speak up and they raise their voice, it may seem like they are now shouting at you.
Recruitment is the result of a reduced dynamic range—that area between the softest sound you can hear and the loudest sound you can stand. Hearing aids need to amplify all sounds so that you can hear them, yet must not amplify them so much that you perceive the louder sounds as painful.
Typically, the greater your hearing loss, the worse your recruitment. Thus, you need to get hearing aids that have good wide dynamic range compression circuitry built in. This compression needs to be set properly for your hearing loss, or loud sounds will "blow the top of your head off." At least that is the way it feels.
Sounds that recruit may seem far too loud, but in reality, this is only your perception of them. In truth, they are not so loud that they are damaging your ears.

4. Hearing Aids Cannot Fix Fuzzy or Distorted Hearing

When you lose your hearing, you not only hear sounds softer, but also speech now sounds fuzzy or distorted. This is because typically you lose most of your hearing in the high frequencies. It is these higher frequencies that give speech much of its intelligence. If your ears can no longer hear these frequencies no matter how much these sounds are amplified, hearing aids will not bring clarity to your fuzzy hearing world.
However, if you still have some high frequency hearing, digital aids can be adjusted to specifically amplify these higher frequencies much more than the lower frequencies you typically hear reasonably well. This will help you hear clearer speech once again. It will not be perfect—so don't expect that—but it will be better.

5. Hearing Aids Do Not Let You Hear Well in Noise

Hearing aids work best in quiet situations when you are only 3 to 8 feet from the speaker. In noise, or at greater distances, hearing aids alone typically do not work well. In fact, not being able to hear in noise is one of the most common complaints of hearing aid users. The truth is, you may hear worse in noise than you do without wearing your hearing aids. For this you just spent £4,000.00?
If you live or work in noisy environments, make sure your hearing aids have good noise suppression circuitry. You will also find that to hear effectively in noise, you will likely need to couple your hearing aids with various assistive listening devices.
Unfortunately, few people even know that assistive technology exists, so they don't insist on having the specific features they need built into their hearing aids in order to couple to this technology.

6. You May Not be Ready Psychologically

Wearing hearing aids before you are ready psychologically is a sure way to fail. You first have to grieve for your hearing loss (i.e. work through the stages of denial, anger, bargaining, and depression before reaching the acceptance stage). It is only when you reach the acceptance stage that you are finally ready to do all you can to help yourself hear better—which includes wearing hearing aids. If you are still in the denial or depression stages, you will not give hearing aids a fair trial before relegating them to the dresser drawer.

Get the Right Hearing Aids and Features

In order to become friends with your new hearing aids, you need hearing aids that are friendly to you and your lifestyle in the first place. "Friendly" hearing aids have the features you need to hear the best you can with your particular hearing loss.
I recommend getting behind the ear (BTE) hearing aids because they are big enough to contain all the "goodies" you need, have the power you may need, last longer, need fewer repairs and are cheaper. In addition, they are easier to put on, easier to manipulate the controls and easier to find when you put them down.
What "goodies" do you need in your hearing aids? In my opinion, you should never buy a hearing aid that does not have a built-in telecoil (sometimes called a T-switch, t-coil or audiocoil). With a telecoil, you can couple effectively to personal amplifiers, FM systems or infrared system via neckloops or silhouettes and to telephones and room loops just via the telecoil. If you have a severe or profound hearing loss, you may also want direct audio input (DAI) capability and/or built-in FM receivers.
If you have to listen to people from a distance or listen when several others are talking, directional microphones can make a big difference. Better yet, get noise-canceling capability combined with directional microphones.

Use Assistive Technology with Your Hearing Aids

Noise and distance are two enemies of hearing aid users. Under these conditions, you need to combine your hearing aids with assistive listening devices such as personal amplifiers, room loops, FM systems and infrared systems. Used together, these devices can turn your hearing aids into super aids.
This is because with these devices, you are effectively moving the microphone from your ears up to the speaker. As a result, you will hear beautiful clear sound in both ears at the same time straight from the speaker's mouth. At the same time, most of the room noise is blocked out—a definite win-win situation.

Good-bye World of Silence! Successfully Adapting to Wearing Hearing Aids

If you have followed the suggestions outlined above, you now have hearing aids that will best fit your needs. You realize that hearing with them won't be perfect, but you'll hear much better than you do now. What you need to do now is learn how to effectively adjust to wearing your new hearing aids so you won't rip them out of your ears in disgust and throw them in a drawer.
In contrast to the opening scenario where the person attempted to wear his hearing aids home from the Audiologists' office, here is a better way to adjust to wearing them.
Sit down and relax in a quiet place in your home. Put your hearing aids in your ears and turn them on. Talk to yourself while you adjust the volume to a comfortable level.
Listen to the sounds around you. Do you hear the hum of the refrigerator? the creaking of your house? the sounds of a car driving by outside? the rustle of your clothes? Get used to them for they will again be a part of your life.
Learn to feel comfortable with your hearing aids. It's normal that your ears will feel full, (and probably hot and sweaty too) like you have something stuffed in them—because you do. If your earmolds hurt, go back to your audiologist to have them ground down a bit. Wearing hearing aids may feel uncomfortable to some degree, but they should never hurt.
On the first day, wear your hearing aids for only one hour. The second day: two hours, the third day: three hours. After that, add another hour a day until you are comfortable wearing them all the time. If this is too fast for you, just increase the time by a smaller amount, say 30 minutes a day.
To begin with, do not wear your hearing aids in noisy places. You need to be comfortable in quiet places first. Treat yourself to easy listening situations during your first few weeks of adjusting to wearing your hearing aids. Try not to listen to too much too soon. If sounds are too loud, turn your hearing aids down slightly. If your hearing aids begin to bother you, take them off and give yourself a rest. Put them on again later. You need time to get used to wearing them and to hearing sounds again. The key to success is to make haste slowly.
Read aloud to yourself. You may be horrified how loud or different your voice sounds. This is normal. Get used to it. This is how you really sound. Slowly you will come to like your "new" voice.
The sound of your phone ringing or the sudden ding-dong of your door bell may startle you. You may jump when doors slam, dogs bark or people cough. This too, is normal.
When you are comfortable hearing your own voice, talk to one other person in a quiet place. Have them sit between 3 and 6 feet from you.
When you are ready, wear your hearing aids outside and listen to the sounds around you. Try to identify birds singing, traffic sounds, rustling leaves, the sounds of your shoes scrunching on the sidewalk. Begin on relatively quiet streets and slowly build up to busy downtown streets.
Finally, but only after you are comfortable wearing your hearing aids in all other situations, are you ready to tackle difficult and noisy listening situations. In crowds and at parties, talk to one person at a time. Don't try to follow everyone at once. If the noise gets to you after a while, seek a quiet place. In restaurants, start with quiet, well-lighted ones. Gradually work up to noisier restaurants as you feel comfortable.
Adjust slowly and consistently to wearing your new hearing aids. You must be patient for it will take time. Remember, it takes from 30 to 90 days for your brain to adjust to the new sounds it is now hearing.
How well and how fast you adapt to your new electronic ears depends on several factors. These include: how bad your hearing loss is, the type of loss you have, how long you have had the loss, whether it happened gradually over many years or whether it was sudden, and how well your ears can discriminate different sounds.
Adapting to your new hearing aids may take a week or a month or a year—everyone is different. The important thing is to keep at it. Don't compare your progress with others.
If you only have a mild loss, you may adapt to your new aids the first day—it may be love at first sound. If your hearing loss is severe you likely will take much longer to adapt. The same is true if you have had a hearing loss for many years before doing anything about it.
However, when you finally adapt to wearing your hearing aids, something surprising happens. The day will come when you will actually feel undressed unless you are wearing your hearing aids. You realize just how much your hearing aids help you successfully cope in the hearing world. Without realising it, you and your hearing aids have become close friends indeed!