Wednesday, 23 October 2013
REM redux
Old post about REM limitations, still relevant though:
If you actually wanted to challenge the veracity of REM measurements, there's a few ways you can make a good case. Namely:
1 The original Audiogram: how accurate is it (and therefore your subsequent target)? Threshold measures are repeatable for some people, but not for everybody. Anyone on here who regularly tests hearing will know that there are patients who 'wander'.
You have also got to consider whether the test was done in noise, with ear-tones or cans, how long ago etc.
2 The probe tube - has to be placed in the last 6mm of the ear canal - not impossible, but it's one of those jobs where an extra hand would be useful, especially if you have a programming lead on the aid. Due consideration for the condition of the ear canal, whether the patient has wax, a cold, a middle ear infection.
3 Target and stimulus tone. People swear by automated speech weighted noise and pseudo random noise. They will also say that a NAL target is better than a DSL. Personally I have massive reservations about using ANY form of stimulus that isn't real speech. Hearing aids are inherently designed to filter noise from within speech channels: if you reproduce a signal or modify it, it contains noise - the aid WILL turn itself down. The best results will always come from straight speech input: not everybody uses this.
4 Loudness experience and patient expectation. Some patients just don't like where the prescription sits, even when you've successfully negotiated all the above. Dealing with this can be difficult: the patient may feel left out of the programming loop or they may just want a different level of loudness than you've arrived at. You have to bear this in mind and soften or louden the settings accordingly. However, it is usually possible to wean them to nearer their prescription over several visits. Other patients sit miles away from their target and are quite happy.
5 Temporal aspects within signals that you can't 'see'. Different manufacturers use different attack and release times as part of their processing strategies, they will make the aid sound different or unnatural, BUT you can't necessarily visualise the response - even on the 3D systems it's not that clear.
If you actually wanted to challenge the veracity of REM measurements, there's a few ways you can make a good case. Namely:
1 The original Audiogram: how accurate is it (and therefore your subsequent target)? Threshold measures are repeatable for some people, but not for everybody. Anyone on here who regularly tests hearing will know that there are patients who 'wander'.
You have also got to consider whether the test was done in noise, with ear-tones or cans, how long ago etc.
2 The probe tube - has to be placed in the last 6mm of the ear canal - not impossible, but it's one of those jobs where an extra hand would be useful, especially if you have a programming lead on the aid. Due consideration for the condition of the ear canal, whether the patient has wax, a cold, a middle ear infection.
3 Target and stimulus tone. People swear by automated speech weighted noise and pseudo random noise. They will also say that a NAL target is better than a DSL. Personally I have massive reservations about using ANY form of stimulus that isn't real speech. Hearing aids are inherently designed to filter noise from within speech channels: if you reproduce a signal or modify it, it contains noise - the aid WILL turn itself down. The best results will always come from straight speech input: not everybody uses this.
4 Loudness experience and patient expectation. Some patients just don't like where the prescription sits, even when you've successfully negotiated all the above. Dealing with this can be difficult: the patient may feel left out of the programming loop or they may just want a different level of loudness than you've arrived at. You have to bear this in mind and soften or louden the settings accordingly. However, it is usually possible to wean them to nearer their prescription over several visits. Other patients sit miles away from their target and are quite happy.
5 Temporal aspects within signals that you can't 'see'. Different manufacturers use different attack and release times as part of their processing strategies, they will make the aid sound different or unnatural, BUT you can't necessarily visualise the response - even on the 3D systems it's not that clear.
Saturday, 21 September 2013
Occlusion Revisited.
Hearing Aid Forums Post About Occlusion and Venting
The degree of occlusion experienced will be down to a few different physical factors:
1 The pathology of the ear canal and the surrounding structures.
2 The depth of the fitting.
3 The degree of low frequency loss.
4 The level and pitch of your voice.
5 The venting of the mould.
People with a pathology that transfers sound well from the vocal chords, will struggle with more occlusion than others.
If the tip of the hearing device goes beyond the point in the ear canal that is reverberating with your own voice then it's less likely that occlusion will be experienced.
Typically people with over 60 dB (in the lower frequencies) losses don't get occlusion as they simply don't hear their unamplified voice anyway. Common high-frequency loss or Presbyacusis, tends to have a milder low frequency component which is often only 20dB or less - this leads to significant awareness of occlusion.
There's an association with a resonance at 500Hz which seems to be where occlusion is most prevalent. If you don't make a 500Hz sound at any great level, its possible you won't experience the same degree of occlusion as someone who does.
Moulds need to be vented properly: as a rule of thumb the following apply -
At low frequency losses greater than 60dB - No venting is needed - though it might be handy to have a pressure vent in there for equalisation.
At low frequency losses 40-60dB, venting around 2 mm is desirable.
20-40dB - venting of 4mm makes things sound a lot better.
0-20dB - As open as possible.
You can see why RIC open fittings are doing well compared with the older more occluded fittings, simply in terms of wearer occlusion comfort they win out due to better venting.
The degree of occlusion experienced will be down to a few different physical factors:
1 The pathology of the ear canal and the surrounding structures.
2 The depth of the fitting.
3 The degree of low frequency loss.
4 The level and pitch of your voice.
5 The venting of the mould.
People with a pathology that transfers sound well from the vocal chords, will struggle with more occlusion than others.
If the tip of the hearing device goes beyond the point in the ear canal that is reverberating with your own voice then it's less likely that occlusion will be experienced.
Typically people with over 60 dB (in the lower frequencies) losses don't get occlusion as they simply don't hear their unamplified voice anyway. Common high-frequency loss or Presbyacusis, tends to have a milder low frequency component which is often only 20dB or less - this leads to significant awareness of occlusion.
There's an association with a resonance at 500Hz which seems to be where occlusion is most prevalent. If you don't make a 500Hz sound at any great level, its possible you won't experience the same degree of occlusion as someone who does.
Moulds need to be vented properly: as a rule of thumb the following apply -
At low frequency losses greater than 60dB - No venting is needed - though it might be handy to have a pressure vent in there for equalisation.
At low frequency losses 40-60dB, venting around 2 mm is desirable.
20-40dB - venting of 4mm makes things sound a lot better.
0-20dB - As open as possible.
You can see why RIC open fittings are doing well compared with the older more occluded fittings, simply in terms of wearer occlusion comfort they win out due to better venting.
Thursday, 29 August 2013
Audiology/Hearing Aid/Sound Glossary of terms produced by the ISVR
Brilliant resource:
A short abstract of the As below. All copyright per the original authors and the ISVR.
Here
A
A short abstract of the As below. All copyright per the original authors and the ISVR.
Here
A
| acoustic admittance | Reciprocal of acoustic impedance. | |
| acoustic coupler | A cavity of specified shape and volume which is used for the calibration of an earphone in conjunction with a calibrated microphone to measure the sound pressure developed within the cavity. Compared to an artificial ear, a coupler embodies only a rough approximation to the acoustic properties of the human ear but has the advantage of simple design and construction. | |
| acoustic feedback | In hearing aids, the condition in which the amplified acoustic signal leaks from the ear canal, is picked up by the microphone and then re-amplified, resulting in a howling or whistling sound. The term is also applied to the feedback sound itself. | |
| acoustic gain | As applied to the testing of a hearing aid, the difference between the output sound pressure level developed in the acoustic coupler or occluded-ear simulator and that measured at the position of the hearing aid microphone. The particular conditions of test have to be specified. Sometimes called transmission gain. | |
| acoustic impedance | Quotient of a sound pressure by the volume velocity produced by it. | |
| acoustic nerve | Alternative term for the cochlear nerve. | |
| acoustic neuroma | Common term for a non-malignant tumour on the VIIIth cranial nerve which, by invading the intracranial spaces, becomes life-threatening. It causes ataxia and neural hearing loss. Also termed vestibular schwannoma or acoustic neurinoma. | |
| acoustic reflex | Contraction of the middle-ear muscles, stapedius and/or tensor tympani, as a normally bilateral response to an acoustic or other eliciting stimulus (which is not necessarily bilateral). The amount of contraction and subsequent acoustic reflex decay (ARD) are measured by immittance audiometry. The reflex is commonly described as ipsilateral or contralateral, depending on which side the response is observed relative to the stimulus. | |
| acoustic reflex threshold | ART | Of an ear and for a specified type of sound, the lowest level of that sound which elicits the acoustic reflex. The reflex is recognized by a change in aural immittance as an increasing stimulus level reaches and surpasses the acoustic reflex threshold. The ART is conventionally expressed in terms of hearing level but use of sensation level is an aid to diagnosis. |
| acoustic trauma | Instantaneous injury to, or destruction of, a component or components of the auditory system resulting from exposure to a very high transient sound pressure, e.g. from explosion or weapons fire. The term is not to be confused with noise-induced hearing loss from chronic exposure or with barotrauma. | |
| action level | One of three levels of noise specified in the Noise at Work Regulations 1989. First action level: a daily personal noise exposure of 85 dB(A); second action level: a daily personal noise exposure of 90 dB(A); peak action level: a peak sound pressure of 200 Pa. These levels define various actions to be taken by employer and employee. | |
| admittance | ............... |
Friday, 2 August 2013
Tuesday, 30 July 2013
Brownian motion and hearing aid mic noise.....
......explained a bit further for Hearing Aid Forums readers.
That's not static, it's the noise floor - caused by air particles hitting the diaphragm of the mic (Brownian motion).
The 'only' (perhaps somebody else has now) people to have dealt with this properly so far are Widex. If you're an engineer you'll get the explanation.
All* the mics used in hearing aids are based on the electret condenser principle. You basically charge a gold/mylar film to a high voltage (permanent) and then move it back and forth over a backplate. The back plate is connected to a MOSFET gate which allows the incoming voltage to be 'switched' on and off. Hence your mic signal. The diaphragm mass is as small as possible to reduce skeletal vibration transfer and be as sensitive as possible. It's also got to be as near to the back-plate as practical to ensure the best attraction/repulsion.
The downside of making the diaphragm smaller is that the effects of Brownian motion become more pronounced and you create a noise floor of 20-30dB before the amplifier stage, especially with the smallest diaphragm mics.
Widex uses a clever system to get around this - by splitting the input (1.0-1.2V) voltage at x GHz into an AC voltage it creates an effective 2.0-2.4V potential across the aid. Which you will know benefits the system as V rises, power consumption falls. The particular benefit with this system is that higher voltage allows the mic diaphragm properties to be altered - moved away/different mass - which can be used to alleviate the effects of Brownian motion. Subsequent noise floor levels are now around 16dB.
Furthermore the Widex system is 16-Bit (96dB range) and only starts sampling at 17 dB - so the entire mic is effectively ignored by the hearing aid UNTIL it starts producing a signal in relation to a real output.
*AFAIK
That's not static, it's the noise floor - caused by air particles hitting the diaphragm of the mic (Brownian motion).
The 'only' (perhaps somebody else has now) people to have dealt with this properly so far are Widex. If you're an engineer you'll get the explanation.
All* the mics used in hearing aids are based on the electret condenser principle. You basically charge a gold/mylar film to a high voltage (permanent) and then move it back and forth over a backplate. The back plate is connected to a MOSFET gate which allows the incoming voltage to be 'switched' on and off. Hence your mic signal. The diaphragm mass is as small as possible to reduce skeletal vibration transfer and be as sensitive as possible. It's also got to be as near to the back-plate as practical to ensure the best attraction/repulsion.
The downside of making the diaphragm smaller is that the effects of Brownian motion become more pronounced and you create a noise floor of 20-30dB before the amplifier stage, especially with the smallest diaphragm mics.
Widex uses a clever system to get around this - by splitting the input (1.0-1.2V) voltage at x GHz into an AC voltage it creates an effective 2.0-2.4V potential across the aid. Which you will know benefits the system as V rises, power consumption falls. The particular benefit with this system is that higher voltage allows the mic diaphragm properties to be altered - moved away/different mass - which can be used to alleviate the effects of Brownian motion. Subsequent noise floor levels are now around 16dB.
Furthermore the Widex system is 16-Bit (96dB range) and only starts sampling at 17 dB - so the entire mic is effectively ignored by the hearing aid UNTIL it starts producing a signal in relation to a real output.
*AFAIK
Monday, 29 July 2013
Thursday, 25 July 2013
Libby Horns and tubing article from the man himself.
Article that covers the changes to a BTE sound output that can be achieved with different tubing set-ups.
http://www.cylibby.com/horn/
http://www.cylibby.com/horn/
Wednesday, 19 June 2013
Sunday, 2 June 2013
Extra low power Bluetooth Chips.....
Coming to a hearing-aid near you soon?
With SmartBond, Dialog Semiconductor has released what the company claims to be the world's lowest power and smallest Bluetooth Smart System-on-Chip (SoC), which more than doubles the battery life of an app-enabled smartphone accessory or computer peripheral in comparison to competing solutions on the market.
Designed to connect keyboards, mice and remote controls wirelessly to tablets, laptops or Smart TVs, the part number DA14580 will enable consumers to use innovative apps on their smartphones and tablets connected with watches, wristbands and smart tags, to “self-track” their health and fitness levels, locate lost keys and much more besides.
SmartBond unique low power architecture draws just 3.8mA at transmission and reception, 50% less than other Bluetooth Smart solutions on the market according to the manufacturer, with a deep sleep current of under 600nA. This means a 225mAh coin-cell battery in a product sending 20 bytes of data per second would last 4 years and 5 months in comparison to just 2 years with previous generations of Bluetooth Smart technology.
The DA14580 features a Power Management block, including a DC-DC converter and all the necessary LDOs, reducing the need for external components and the overall bill of materials. By precisely switching on and off power delivery to each block on the chip, Dialog is able to reduce energy consumption to a bare minimum.
SmartBond works at much lower voltages than was previously possible, down to 0.9V, enabling the use of just one alkaline or NiMH cell AA battery instead of two in computer or smart TV peripherals. The DA14580 comes in three different form factors, the smallest Wafer-Level Chip-Scale package measures 2.5x2.5x0.5mm.
Visit Dialog Semiconductor at www.dialog-semiconductor.com
Find more datasheets on products at Datasheets.com, searchable by category, part #, description, manufacturer, and more.
Don't miss out on the latest products. Subscribe to EDN's weekly Products & Tools newsletter (free registration) for the latest product announcements and news.
This article originally appeared on EE Times Europe.
Saturday, 18 May 2013
BSHAA 18/05/13
BSHAA 17/05/13 pm
UCL Dr David McAlpine
Cocktail Party SNR issues.
Negative SNR possible thru natural hearing.
Separation of signal via brain. Binaural construction of 'sound' at retro-cochlear level. Localization and spatial release from masking noise.
Social aspect of Binaural hearing.
Duplex theory of binaural hearing. Raleigh et.....
Interaural level dependency: HF
Temporal difference - discovered through phase differential. LF.
Observable binaural beats - phase shifting of diff frequency sound 'rotates' through stereo spectrum.
Binaural - unmasking; invert one signal to lift it from the noise.
Reflected surfaces - don't just use direct paths. Make the signal far more complex.
Integrating info across both ears: binaural presentation essential to tell differences.
Limits of Binaural Hearing: still front/back issues. Ear localisation - pinna allows boosted signals. You need over a month to adapt to 'new' ears.
Restoration? Do hearing aids restore binaural hearing? Compression might be an issue - linearity makes things better - FPL.??
Dr. Todd Ricketts
Hearing aid features.....12 classes of features.
8 minors - Beamforming, Sophisticated Gain Processing, Tinnitus Masking, Bilateral sharing info; spatialization correction, remote mics, Extended HF - related to slope of loss, shallower slope better. Frequency lowering: no average benefit in adults. Trainable algorithms - some px, not all.
4 main areas; A-F grading/Target Px/Manufacturer Differences.
Digital Noise reduction: Gain lowering
Fast Filtering : takes out noise between speech.
Results - Comfort improved, perceived quality improved - doesn't make SNR worse in adults: but no improvement in SNR. Less listening effort? -6dB not helping.
DNR: Real World Benefit: C, Application: B+,MFR: SD
FBM performance - phase cancelling etc.
Widened application of hearing aids etc....
Issues - Entrainment, speed, effective magnitude.
Measure REAR using stored probe tube calibration - open fit. Fixed position - does it cause problems? Not with live speech signal.
Big variation in efficacy of FBM systems, lots of variation in gain
Also variation in speed of FBM - Phone 'chirp'
FBM: RWB A-, App; A+, MFR: LD
Frequency Compression in Mild/Mod losses.
Limited performance S sound only.
Doesn't hurt that much.
FC: RWB C-, MFR N/A,Mfr: MD
Wireless Routing Capability: Streamer device etc.
Issues with streamers - direct routing to come/battery issues.
Improved SNR etc.
Advantage limited for bilateral open fitted; marginal.
Closed fitting much better. Turn off outside mic.
Better than telecoil/ bilateral better again.
Positioning issues resolved
Wireless BC/B-/LD.
Mel Ferguson - NIHR
10 million in UK with loss. 70+ years.
20% ITD HA. -£30m wasted.
Auditory Training - Does it work? Improvements - some evidence.
No improvement of speech in noise.
Friday, 17 May 2013
Bshaa 17/05/13 PM
BSHAA 17/05/13 pm
UCL Dr David McAlpine
Cocktail Party SNR issues.
Negative SNR possible thru natural hearing.
Separation of signal via brain. Binaural construction of 'sound' at retro-cochlear level. Localization and spatial release from masking noise.
Social aspect of Binaural hearing.
Duplex theory of binaural hearing. Raleigh et.....
Interaural level dependency: HF
Temporal difference - discovered through phase differential. LF.
Observable binaural beats - phase shifting of diff frequency sound 'rotates' through stereo spectrum.
Binaural - unmasking; invert one signal to lift it from the noise.
Reflected surfaces - don't just use direct paths. Make the signal far more complex.
Integrating info across both ears: binaural presentation essential to tell differences.
Limits of Binaural Hearing: still front/back issues. Ear localisation - pinna allows boosted signals. You need over a month to adapt to 'new' ears.
Restoration? Do hearing aids restore binaural hearing? Compression might be an issue - linearity makes things better - FPL.??
Dr. Todd Ricketts
Hearing aid features.....12 classes of features.
8 minors - Beamforming, Sophisticated Gain Processing, Tinnitus Masking, Bilateral sharing info; spatialization correction, remote mics, Extended HF - related to slope of loss, shallower slope better. Frequency lowering: no average benefit in adults. Trainable algorithms - some px, not all.
4 main areas; A-F grading/Target Px/Manufacturer Differences.
Digital Noise reduction: Gain lowering
Fast Filtering : takes out noise between speech.
Results - Comfort improved, perceived quality improved - doesn't make SNR worse in adults: but no improvement in SNR. Less listening effort? -6dB not helping.
DNR: Real World Benefit: C, Application: B+,MFR: SD
FBM performance - phase cancelling etc.
Widened application of hearing aids etc....
Issues - Entrainment, speed, effective magnitude.
Measure REAR using stored probe tube calibration - open fit. Fixed position - does it cause problems? Not with live speech signal.
Big variation in efficacy of FBM systems, lots of variation in gain
Also variation in speed of FBM - Phone 'chirp'
FBM: RWB A-, App; A+, MFR: LD
Frequency Compression in Mild/Mod losses.
Limited performance S sound only.
Doesn't hurt that much.
FC: RWB C-, MFR N/A,Mfr: MD
Wireless Routing Capability: Streamer device etc.
Issues with streamers - direct routing to come/battery issues.
Improved SNR etc.
Advantage limited for bilateral open fitted; marginal.
Closed fitting much better. Turn off outside mic.
Better than telecoil/ bilateral better again.
Positioning issues resolved
Wireless BC/B-/LD.
Mel Ferguson - NIHR
10 million in UK with loss. 70+ years.
20% ITD HA. -£30m wasted.
Auditory Training - Does it work? Improvements - some evidence.
No improvement of speech in noise.
Bshaa 17/05/13 AM
Dr.Sweetow: Tinnitus...
Theories:
Disruption of Auditory Input
Decrease of inhibtory function: efferent
Other inputs - collateral inputs from touch/feel/sight/TMJ function
Neuron acivity
Fear and Threat - limbic function
Other brain function.
Possible cure through gating function in lower brain areas/basal ganglia - hypothalamus area. Deals with phantom perception.
Ability to relax impaired through whole brain: px brain waves altered.
Stress - major factor - Empirical evidence.
BRAIN function - Cut auditory nerve Tx still present.
Tx Px have - ABNORMAL GATING.....(inability to ignore or filter)
historical approaches: Adjustment via auditory input: hearing aids, masker, ipod etc. Neuromonics, Soundcure. Zen tones.
Limbic approaches: CBT etc,TRT. Instructional approaches. Antidepressants.
New stuff: Cortical intervention etc.
Not all strategies effective: Px has to believe delivery.
Tx closely aligned with sleep issues/stress/attention/emotion etc.
Treatment:
Counselling: give px Widex questionnaire.
Review - with spouse.
Instructional Counselling - Phys/Anat, NORMAL for hearing loss, difficulties: define when where how.
Habituation: process of "Ignoring" - somatosensory cortex analysis - hippocampus: identify, Amygdala - limbic threat or not = cerabellum - move on depending on risk.
Tinnitus px = chronic state of anxiety, stress etc.
Friday, 10 May 2013
Wednesday, 8 May 2013
Moxi Kiss Launch.
New Unitron 312 shell-set.
Loses telecoil option, becomes longer; but apparently that's all better because it was designed by Californians and a few focus groups.
Here.
Loses telecoil option, becomes longer; but apparently that's all better because it was designed by Californians and a few focus groups.
Here.
Friday, 3 May 2013
Bionic Ear: a bit of the future.....
Latest 3d printing techniques and some pretty fancy materials combined with some high end bioscience could see this sort of thing becoming the norm in few years time.
http://news.cnet.com/8301-17938_105-57582634-1/printable-bionic-ear-sends-hearing-to-the-dogs/?part=rss&subj=news&tag=title
http://news.cnet.com/8301-17938_105-57582634-1/printable-bionic-ear-sends-hearing-to-the-dogs/?part=rss&subj=news&tag=title
Monday, 22 April 2013
APD - Auditory Processing Disorder
APD on-line lecture
Introduction into the team in the SIG group and opportunity to follow up their work in more detail.
Introduction into the team in the SIG group and opportunity to follow up their work in more detail.
Friday, 19 April 2013
Sonova cochlear implant trial.
Sonova in a bit of bother over their Cochlear Implant programme: the ability to adequately seal the components has always been a major issue. Long term hermetic sealing is obviously an integral design consideration.
LOUISVILLE, Ky. (AP) — A central Kentucky family won a $7.24 million verdict after a jury concluded that a company that makes implantable hearing aids knowingly sold a defective device that shocked a 6-year-old girl.
The jury in federal court in Louisville awarded $6.25 million in punitive damages and $994,000 in compensatory damages on Wednesday to the family of Breanna Sadler of Vine Grove. Sadler's family sued Advanced Bionics in 2011 — about three years after the girls' cochlear implant made her ill and sent her into convulsions when moisture seeped into the device.
Attorney Ronald Johnson, who represents the Sadler family and focuses on medical device litigation, said the company was "defiant" about whether it had done anything wrong in handling the hearing aid.
"This is, without a doubt, the worst conduct I've ever seen by a corporation, especially when dealing with such a vulnerable population," Johnson said.
The Swiss parent company of Advanced Bionics, Sonova, said in a written statement that it will consider appealing the judgment. In court records, the company said the devices complied with all federal regulations and recalls were issued appropriately.
The jury's award is the third largest in the western district of Kentucky since 1998, said Shannon Ragland, who runs the Kentucky Trial Court Review, a publication that monitors jury verdicts and awards.
A cochlear implant, sometimes called a bionic ear, is a device that is surgically placed into the bone of a patient's skull. Wires attach it to a magnet, which rests on the person's skull. When the magnet is engaged, the device gives a profoundly deaf or hard of hearing person a sense of sound.
The device has gained popularity among parents who have children with profound hearing issues, such as the one suffered by Breanna Sadler.
Breanna was 4 in 2006 when her family decided to have the cochlear device implanted.
"It worked pretty well," Johnson said. "It was a big surgery and they had it."
Breanna Sadler's device malfunctioned on Dec. 29, 2008. Johnson said her mother heard the girl screaming and found Breanna rubbing her head on the carpet and having convulsions. After calming the girl down, the mother removed the magnet from the device.
"When she did, the convulsions stopped," Johnson said.
A doctor reattached the magnet, prompting more illness, screaming and convulsions, Johnson said. Six weeks later, Breanna underwent surgery to remove the Advanced Bionics device and have a new brand implanted.
Tests later showed that the device inside Breanna Sadler's ear had over 30 percent moisture. The allowable amount of moisture is .5 percent.
"She was at 60 times the allowable amount," Johnson said.
Advanced Bionics first became aware of problems with the implant in 2004 and conducted a limited, six-week recall in which they ceased shipping the devices. In March 2006, the company recalled devices that hadn't been implanted because of the issue of excessive moisture seeping into the device.
The company shipped roughly 4,000 implants between the 2004 recall and the 2006 recall. The Food and Drug Administration cited Advanced Bionics in 2007 for failing to get approval for a new supplier of a component to keep moisture out of the device. The FDA and Advanced Bionics settled the charges in 2008 for $1.1 million.
"It was too late for Breanna," Johnson said.
To date, more than 1,000 have malfunctioned — a failure rate of about 40 percent. Johnson said the rate could rise to as high as 50 percent.
"If they're lucky, they just won't be able to hear anymore," Johnson said.
Breanna is now 11-years-old and the impact of the two surgeries and malfunctioning have taken a toll on her, Johnson said.
"Anytime she hears anything, she jumps out of her skin. She's very, very apprehensive," Johnson said. "She's just a very, very fearful little girl now."
The jury in federal court in Louisville awarded $6.25 million in punitive damages and $994,000 in compensatory damages on Wednesday to the family of Breanna Sadler of Vine Grove. Sadler's family sued Advanced Bionics in 2011 — about three years after the girls' cochlear implant made her ill and sent her into convulsions when moisture seeped into the device.
Attorney Ronald Johnson, who represents the Sadler family and focuses on medical device litigation, said the company was "defiant" about whether it had done anything wrong in handling the hearing aid.
"This is, without a doubt, the worst conduct I've ever seen by a corporation, especially when dealing with such a vulnerable population," Johnson said.
The Swiss parent company of Advanced Bionics, Sonova, said in a written statement that it will consider appealing the judgment. In court records, the company said the devices complied with all federal regulations and recalls were issued appropriately.
The jury's award is the third largest in the western district of Kentucky since 1998, said Shannon Ragland, who runs the Kentucky Trial Court Review, a publication that monitors jury verdicts and awards.
A cochlear implant, sometimes called a bionic ear, is a device that is surgically placed into the bone of a patient's skull. Wires attach it to a magnet, which rests on the person's skull. When the magnet is engaged, the device gives a profoundly deaf or hard of hearing person a sense of sound.
The device has gained popularity among parents who have children with profound hearing issues, such as the one suffered by Breanna Sadler.
Breanna was 4 in 2006 when her family decided to have the cochlear device implanted.
"It worked pretty well," Johnson said. "It was a big surgery and they had it."
Breanna Sadler's device malfunctioned on Dec. 29, 2008. Johnson said her mother heard the girl screaming and found Breanna rubbing her head on the carpet and having convulsions. After calming the girl down, the mother removed the magnet from the device.
"When she did, the convulsions stopped," Johnson said.
A doctor reattached the magnet, prompting more illness, screaming and convulsions, Johnson said. Six weeks later, Breanna underwent surgery to remove the Advanced Bionics device and have a new brand implanted.
Tests later showed that the device inside Breanna Sadler's ear had over 30 percent moisture. The allowable amount of moisture is .5 percent.
"She was at 60 times the allowable amount," Johnson said.
Advanced Bionics first became aware of problems with the implant in 2004 and conducted a limited, six-week recall in which they ceased shipping the devices. In March 2006, the company recalled devices that hadn't been implanted because of the issue of excessive moisture seeping into the device.
The company shipped roughly 4,000 implants between the 2004 recall and the 2006 recall. The Food and Drug Administration cited Advanced Bionics in 2007 for failing to get approval for a new supplier of a component to keep moisture out of the device. The FDA and Advanced Bionics settled the charges in 2008 for $1.1 million.
"It was too late for Breanna," Johnson said.
To date, more than 1,000 have malfunctioned — a failure rate of about 40 percent. Johnson said the rate could rise to as high as 50 percent.
"If they're lucky, they just won't be able to hear anymore," Johnson said.
Breanna is now 11-years-old and the impact of the two surgeries and malfunctioning have taken a toll on her, Johnson said.
"Anytime she hears anything, she jumps out of her skin. She's very, very apprehensive," Johnson said. "She's just a very, very fearful little girl now."
Friday, 5 April 2013
Battery or Body powered hearing aids.....
Here:
Looking into using the body's own electricity to power your hearing aid.
Practical considerations: where do you shove the electrodes? ;)
Looking into using the body's own electricity to power your hearing aid.
Practical considerations: where do you shove the electrodes? ;)
Wednesday, 27 March 2013
Interesting refresher on dB SPL vs dB HL
Copyright Neil Bauman 2011.
by Neil Bauman, Ph.D.
A student asked,
What is the relationship between the SPL dB scale and HL dB scale?
Good question. I’ll bet there are lots of hard of hearing people that are unclear about the differences between those two scales, and often treat these two terms as though they are interchangeable and mean the same thing—if they even wonder about those acronyms on their audiograms.
When audiologists measure your hearing, they measure your hearing in units called decibels (dB). The catch is that there are several decibel scales. Thus, in order to be meaningful, your audiologist indicates which decibel scale she used. The two most commonly used scales are the SPL (Sound Pressure Level) and the HL (Hearing Level) scales.
Sound meters are calibrated in dB SPL. This makes total sense because the condenser microphones used in sound meters are sensitive to changes in sound pressure in the air, just as our ears are. In contrast, audiometers are calibrated in dB HL, not in dB SPL like you would think would be done. This begs the question, “Why not calibrate audiometers using the SPL scale and forget about the HL scale?”
Here’s the reason why. Our ears do not hear equally well at all frequencies. If our ears heard all
frequencies of sound equally well, then we wouldn’t need the HL scale.
Our ears do not perceive low- and high-frequency sounds as well as they do sounds between 500 and 4,000 Hz. For example, the faintest sound a young person with normal hearing can hear at 2,500 Hz is 0 dB SPL. In contrast, at 20 Hz (a very low frequency sound), the sound needs to be much louder at 72 dB SPL in order to just faintly hear it. At the other end of the frequency spectrum, a very high-pitched sound at 15,000 Hz needs to be increased to 20 dB SPL in order for you to just detect it.
Thus, normal hearing, if plotted on an audiogram using the SPL scale, would be a curved, wavy line and look like the bottom line in Fig. 1. Since this line is both curved and somewhat wavy, it would be difficult to readily tell on an audiogram how much hearing loss a person has by frequency.
It would be ever so much easier to visualize the degree of hearing loss if normal hearing showed as a flat, straight line set at 0 dB on the audiogram. Then, any deviation from this line would indicate the degree of hearing loss.
This is the reason why they developed the HL scale. The curved SPL scale is normalized so that it becomes a flat, straight line at 0 dB. (We call this normalized SPL scale the HL scale.)
Using the HL scale, normal (“perfect”) hearing is a straight line across the top of an audiogram. When your audiologist tests you, any deviation from the 0 dB HL line indicates a hearing loss if it falls below the 0 dB line. (By the same token, if your hearing deviates above the 0 dB line, you have better than normal hearing at that frequency.)
To convert SPL readings to HL readings, audiometers are calibrated to add a specific amount to each frequency tested. This amount varies by frequency. For example, at 125 Hz, it adds 45 dB, while at 1,000 Hz it only adds 7 dB. Likewise, at 4,000 Hz it adds in 9.5 dB, while at 8,000 Hz it adds in 13 dB.
The result is that now your audiogram readily shows your hearing loss graphically in dB HL, rather than you trying to mentally visualize the degree of hearing loss if it were plotted in dB using the SPL scale.
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