Hearing Aid Research and Technology
Hearing aids are technological marvels, and their features are changing
at an amazing pace. Much of the technology that makes today's hearing
aids so effective wasn't even available just a few years ago. It's a
tough assignment, but we intend to keep abreast of all the developing
hearing aid technology and report on it as it happens!
May 2013 - Purdue innovation could help people with
severe hearing loss
April 2013 - Listen Up To Smarter, Smaller Hearing Aids
March 2013 - Use your Android phone as a hearing aid
remote
February 2013 - Digital Hearing Aids Vs. Analog Hearing
Aids
February 2013 - A waterproof hearing aid
January 2013 - Cognitive Function, Speech Reception, and
Hearing Aid Fitting
December 2012 - MIT Researchers Power Radio Chip from
Ear's "Natural Battery"
November 2012 - Software Improves Quality of Sound
for Hearing Aid Users
November 2012 - Siemens Releases New Hearing Aid
Technology
October 2012 - New Hearing Aid to Improve Hearing in
Noise
August 2012 - The Effects of Frequency-Lowering on
Speech Understanding in Children
July 2012 - Hearing-aid hackers fine-tuning their own
devices
April 2012 - New hearing-aid technology
February 2012 - The Effectiveness of Frequency Lowering
Hearing Aids
January 2012 -
Programming hi HealthInnovations'
Hearing Devices
January 2012 - Bringing
Rechargeable Hearing Aids into the Mainstream Market
December 2011 - Panasonic Expands on
Hearing Instrument Lineup
December 2011 -
Digital Wireless Hearing Aids, Part 4: Interference
November 2011 - Solar Ear CEO Named Social
Entrepreneur of the Year
October 2011 -
Understanding the Terms "Water Resistant" and
"Waterproof"
September 2011 -
Phone and TV Solutions for Better
Hearing
August 2011 - Hearing aids running on
methanol
August 2011 - Digital Wireless
Hearing Aids, Part 3: Audiological Benefits
July 2011 -
ReSound Releases Dual-Microphone Wind Noise
Reduction Technology
June 2011 - Audiotoniq Announces
Revolutionary High-Tech Hearing System
June 2011 - Siemens Releases Waterproof,
Dustproof, Shock-Resistant Hearing Aid
April 2011 -
Siemens Introduces New Products Including
Waterproof Hearing Aid
April 2011 -
New Hearing Aid Has Microphone in Ear Canal
March 2011 - ReSound iSolate(tm) Nanotech Reduces Moisture
Related Repairs By 50%
March 2011 - Invisible Extended Wear Hearing
Aids
March 2011 - Speech-in-Noise Potential of Hearing Aids
with Extended Bandwidth
March 2011 - Connectivity in 2011: Enhancing the Human
Experience
January 2011 - New algorithm automatically adjusts
directional system for special situations
December 2010 - When your hearing aid gets wet
December 2010 - Comparison of Wireless and Acoustic
Hearing Aid-Based Telephone Listening Strategies
November 2010 - Technology
shows promise in reducing telecoil interference
November 2010 -
Hearing Aids Must Keep Acoustic Clues Natural
November 2010 - How to Compare Feedback Suppression
Algorithms in Open-Canal Fittings
November 2010 - Tuning in to a
new hearing mechanism
November 2010 - Frequency Transposition: Training Is
Only Half the Story
October 2010 -
Some Comments on Hearing Aid Features
October 2010 -
Peak clipping revisited: Turning distortion to
listener advantage
September 2010 - Can
Spectral Enhancement Improve YOUR Hearing?
September 2010 -
Six ways to improve listening to music through
hearing aids
September 2010 -
Programming hearing instruments to make live music
more enjoyable
September 2010 -
Enhancing music with virtual sound sources
August 2010 -
A New Approach to Nonlinear Signal Processing
August 2010 -
Designing hearing aid signal processing to
reduce demand on working memory
August 2010 -
Evaluation of frequency compression and
high-frequency directionality
July 2010 - Fewer Wires, Less
Complexity, and More Connections: The New Challenge for Wireless Hearing
Instruments
July 2010 -
Solving the trade-off between speech
understanding and listening comfort
June 2010 -
HLAA Convention:
Hearing Aid Research and Development - Part One
June 2010 -
HLAA Convention:
Hearing Aid Research and Development - Part Two
June 2010 -
HLAA Convention:
Hearing Aid Research and Development - Part Three
May 2010 - 3-D imaging technology
could lead to hearing aids that fit better
April 2010 - HIA and EHIMA Partner on HA Interference
Study
April 2010 - Interpreting the efficacy of
frequency-lowering algorithms
March 2010 - Boomers Demanding More Technology in
Hearing Aids
October 2009 - Programming hearing aids using speech
rather than beeps!
August 2009 - New Software Promises Better Speech
Recognition for Hearing Aids and Cochlear Implants
August 2009 - New Hearing Aid Software Improves
Speech Recognition
May 2009 - Environmentally Adaptive Hearing Aids
May 2009 - What's next in hearing instrument
technology?
April 2009 - Frequency-lowering Hearing Aids:
Increasing the audibility of high-frequency speech sounds
March 2009 - Multicore processor powers hearing aid
February 2009 - Audigence, Audina and UF Team to
Improve Hearing Aid Performance
January 2009 -
Bluetooth and Hearing Aids: Ready for
prime time?
December 2008 -
New discovery leading towards intelligent hearing aids
July 2008 - IntriCon Unveils New
High-Performance DSP Hearing Aid Amplifier
March
2007 - Binaural Processing in Hearing Aids?
October 2006 - Here's Mark Ross with a
great article on Feedback Cancellation Systems and Open-Ear Hearing Aid
Fitting.
August 2006 - The History of Hearing Aid
Technology
July 2006 - ASU Pursues High Tech Hearing Loss
Solutions
July 2004 - The previous article talked about enabling your hearing
aids to be bluetooth compatible. This article talks about
using bluetooth to build a much cheaper and more
powerful hearing aid!
June 2004 - Directional microphones don't work very well because the
physical devices are just too small. It's a law of physics - or at least
it was until scientists studied an amazing little fly
that defies physical laws!
July 2002 - Want to know the what one of the premiere experts on
hearing loss and hearing aids thinks about current hearing aid research.
Here's a report on
Mark Ross' workshop at the 2002 SHHH Convention in Seattle.
More on this and related
topics
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April 2013
After losing so much of his hearing, Einhorn says,
he wasn't sure whether he would still be able to work as a composer. So he
began investing in technology that could help him make the most of the
hearing he had left. Einhorn bought a top-of-the-line digital hearing aid
for his left ear. He also went on to buy devices that help him hear what
he's composing, talk on the phone, listen to live music, and carry on
conversations in noisy restaurants. The solutions aren't perfect, Einhorn
says. But they're pretty good. "I compose every day. I see my friends. I go
to movies. I go to concerts. I do everything," he says. All that would have
been a lot harder if Einhorn had lost his hearing just a couple of decades
ago. Back then, most hearing aids were still analog devices with severe
limitations. But in the digital age, hearing aids and so-called assistive
listening devices have become smaller, smarter and much more powerful. The
history of digital hearing aids goes back to the 1980s, says Matthew Bakke,
a scientist at Gallaudet University who also directs the government's
Rehabilitation Engineering Research Center on Hearing Enhancement. Bakke
recalls helping to build a device that was "the size of a refrigerator." But
like all things digital, it shrank fast. By the 1990s, digital hearing aids
had gotten small enough to wear behind the ear. And they've at least
mitigated many of the problems that plagued earlier devices, Bakke says.
Full Story
~~~~~~~~~~~~~~~~~
March 2013
Beltone, a leader in patient-focused hearing
technology for over 70 years, has announced SmartRemote(tm)-the first-ever
app that allows hearing aid wearers to use their Android phone as a "remote
control" to discreetly adjust their hearing instruments. SmartRemote can be
downloaded from Google Play at no cost. Beltone developed the SmartRemote
app in response to what hearing aid wearers wanted most: a great listening
experience in multiple environments, ease-of-use, and complete discretion.
Beltone's award-winning 2.4 GHz wireless streaming technology underpins the
new SmartRemote app. By pairing their hearing aids with the new Direct Phone
Link 2 and the SmartRemote app on their Android phone, the hearing
instrument wearer can use their Android phone to privately adjust hearing
aid volume in one or both ears, change listening programs to match their
environment, mute background noise during a phone conversation, and more.
Full Story
~~~~~~~~~~~~~~~~~
February 2013
A lot of hearing-impaired people would be more
active if they weren't afraid of damaging hearing aids that don't like the
humidity of gyms or the dousings of personal watercraft. In response,
Siemens has introduced what it says is the first waterproof hearing aid,
capable of working as deep as 3 feet under water. The Aquaris can also be
connected to a Bluetooth remote, called the Minitek, that streams audio to
the earpieces, so a person could listen to music from a Bluetooth music
player when swimming, for instance. Or an accessory microphone can be worn
by someone you need to pay close attention to in a noisy room. A survey by
Siemens found that of 500 hearing aid owners, 17 percent restricted their
activity to avoid damaging their hearing aids. That is particularly hard on
groups like hearing-impaired children and people who work at jobs where
there is dust or grime, like farmers or steel workers.
Full Story
~~~~~~~~~~~~~~~~~
January 2013
Effects of cognitive functions on a person's speech
understanding and hearing aid fitting have received a lot of attention in
recent years. Akeroyd examined 20 studies on the association between
cognitive functions and speech reception/recognition in background noise (Int
J Aud 2008;47[Suppl 2]:S53), and the results, when combined with those of
Humes and colleagues, indicate that working memory and the degree of hearing
loss were the most effective predictors for an individual's speech reception
and recognition in noise. (J Speech Hear Res 1994;37[2]:465; J Acoust Soc Am
2002;112[3 Pt 1]:1122; J Speech Lang Hear Res 2007;50[2]:283.)
A person's working memory capacity generally can be
measured in three ways:
Full Story
~~~~~~~~~~~~~~~~~
August 2012
Clinicians are often faced with decisions about
engaging frequency-lowering signal processing in their patients' hearing
aids. Frequency-lowering is designed to move high-frequency sounds to lower
frequencies, where limited hearing and hearing aid bandwidth are less likely
to reduce audibility. Increasing access to high-frequency sounds is
particularly important for hearing-impaired children who may need
high-frequency speech sound audibility to maximize speech understanding.
(Arch Otolaryngol Head Neck Surg 2004;130[5]:556.) The clinical
decision-making process for frequency-lowering can be complicated. Four
different approaches are currently available, and each manufacturer has a
different philosophy about how to lower high-frequency sounds and whether it
should be engaged at all times or only when selected by the patient. Widely
varied outcomes across research studies, even with the same type of signal
processing, add to the confusion. A commonly used and well researched type
of frequency-lowering, nonlinear frequency compression (NFC) can help
clinicians understand the factors that influence outcomes with this
technology.
Full Story
~~~~~~~~~~~~~~~~~
July 2012
If you are short-sighted, usually all it takes is a
visit to an optician to get a pair of spectacles to help restore the world
to sharp detail. But if you suffer hearing problems, visiting an audiologist
just the once will probably not restore sounds to crisp clarity. The
consequent frustration is driving some people with the appropriate expertise
to hack into their own hearing aids to carry out DIY improvements. Brian
Moore, professor of audiology at the University of Cambridge, explained:
"It's not the same as spectacles where you know you have the right
prescription. With a hearing aid you can have an initial prescription but
you will need to do some fine-tuning around that afterwards to satisfy the
individual person." He said the tuning process was frustrating because of
the difficulty in making hearing aids work within different levels of noise.
Full
Story
~~~~~~~~~~~~~~~~~
April 2012
Digital advances have made today's hearing aids
smaller, smarter and easier to use. And microchips, laser beams and even
insects may help create a more crystal-clear experience in the future.
Research at Arizona State University, Cornell University and other
institutions is assisting in the push to improve hearing and reduce the cost
just as millions of baby boomers and Gen Xers are expected to boost demand
for the devices. The technology already has evolved dramatically from the
ear trumpets of the 1860s. Engineers and medical professionals made
significant, recent improvements in the quality of hearing aids and said
they expect to see additional breakthroughs within the next year. One recent
advance is the ability to identify and amplify desired sounds such as a
human voice while muting background noise, said Jerry Ruzicka, president of
Starkey Laboratories Inc., which makes hearing aids.
Full Story
~~~~~~~~~~~~~~~~~
February 2012
Not long ago, the author had a conversation with a
sales rep from one of the major hearing aid manufacturers. He remarked that
it was looking as if frequency-lowering technology (FLT) would become the
"next big thing" in hearing aids, and I asked if the sales rep's company had
any plans to look at incorporating FLT in their hearing aids. His response
was "Well...you know...the literature says it doesn't work." At first glance
of the literature, this is not an unreasonable conclusion; however, when
examined more closely, his statement becomes questionable. . . . Patients
with precipitous high frequency hearing loss have presented challenges to
hearing care professionals since hearing aids were first dispensed.
Precipitous high frequency hearing loss can have serious effects on speech
understanding. High frequency speech components, particularly voiceless
consonants, may be inaudible. In these instances, attempts to make these
sounds audible are usually fruitless due to the dearth of sensory cells in
the region of the cochlea responsible for the coding of these sounds, or
even the presence of cochlear dead regions. Conventional amplification
schemes can be of limited or no utility with this kind of hearing loss.
Full Story
~~~~~~~~~~~~~~~~~
December 2011
With the wide array of high-tech gadgets in use
today, it is inevitable that interference will pose challenges for hearing
aids. Very often it can be difficult to determine the exact source of
interference, but it is helpful if the patient can describe the environment
where interference is noted. This article explains the various forms and
routes of interference, and provides practical advice about mitigating
interference problems in digital wireless hearing aids.
Full Story
~~~~~~~~~~~~~~~~~
October 2011
Moisture and electronics do not make good
companions. Damage from moisture is one of the leading reasons for hearing
aid repair. Common problems are electrical shortages, condensation, and
corrosion. Additionally, moisture can clog the air holes of the zinc air
battery. This unwanted moisture can be from weather/humidity, the
perspiration of the user, or accidental water incidents. Problems associated
with moisture in hearing aids can be very frustrating for the patient, as
often the hearing aid "dies" unexpectedly, with no quick remedy available.
Over the years, there have been many attempts to solve the hearing aid
moisture problems. Devices, such as protective wrappers or sleeves,
dehumidifying kits, and special hearing aid dryers, have been introduced.
More recently, special nanocoatings have been used that make the hearing
aids water-resistant-a significant improvement over hearing aids of previous
generations. But is water-resistant good enough?
Full Story
~~~~~~~~~~~~~~~~~
July 2011
ReSound has announced that it has developed wind
noise reduction technology called WindGuard. The dual-microphone signal
processing technology will be available in September 2011 with the release
of ReSound's upgraded Aventa fitting software. ReSound's Surround Sound
Processor is one feature that is already designed to reduce wind noise.
Since wind noise is predominantly a low-frequency sound, it is typically a
greater problem for directional hearing aids. The Surround Sound Processor
incorporates low-frequency sound inputs that are processed omnidirectionally.
However, wind noise still remains an issue for some users. WindGuard acts as
a second line of defense against wind noise in both directional and
omnidirectional microphone modes.
Full Story
~~~~~~~~~~~~~~~~~
April 2011
It has long been known that, when the microphone is
moved from the top of the ear (as in BTEs) to somewhere inside the auricle
(as in ITEs), a high frequency boost occurs, as the auricle acts as a
natural acoustic preamplifier-with potential benefits in directivity and
localization. Unlike a traditional RIC, a new microphone and receiver in the
canal (MaRiC) design by ExSilent incorporates a small canal-worn module that
contains both the microphone and receiver, as well as an over-the-ear
processing unit to take maximum advantage of the high frequency focusing
ability of the auricle, as well as other attractive features provided by RIC
devices.
Full Story
~~~~~~~~~~~~~~~~~
March 2011
ReSound, the technology leader in hearing solutions,
has released results from a recent study into the iSolate(tm) nanotech
protective coating for hearing instruments. In a review of 50,000 hearing
aids sold, the iSolate(tm) nanotech protective coating was shown to decrease
moisture and debris related repairs by 50% in the first six months. "The
benefits of iSolate(tm) nanotech become more evident with time," said
Jennifer Groth, Global Audiology, ReSound. "We expect even better results at
the 9 - 12 month mark."
Full Story
~~~~~~~~~~~~~~~~~
March 2011
This study shows that a hearing aid with an extended
bandwidth may improve the wearer's tolerance for noise in a noisy
environment. However, to achieve this improvement, the prescriptive gain
target needs to accommodate the added bandwidth of the hearing aid.
Full Story
~~~~~~~~~~~~~~~~~
March 2011
Digital advances have made today's hearing aids
smaller, smarter and easier to use. And microchips, laser beams and even
insects may help create a more crystal-clear experience in the future.
Research at Arizona State University, Cornell University and other
institutions is assisting in the push to improve hearing and reduce the cost
just as millions of baby boomers and Gen Xers are expected to boost demand
for the devices. The technology already has evolved dramatically from the
ear trumpets of the 1860s. Engineers and medical professionals have made
significant, recent improvements in the quality of hearing aids and said
they expect to see even more breakthroughs within the next year.
Full Story
~~~~~~~~~~~~~~~~~
by Douglas L. Beck, AuD, and Marcus Holmberg, PhD
March 2011
Three significant benefits previously available only
through FM systems-including reduced background noise, reverberation, and
high SNR-are attained by a new wireless remote microphone from Oticon. The
ConnectLine Microphone transmits wireless signals from virtually any sound
source (within about 40 feet) directly into the Streamer, which then sends
the audio signal to two wireless-enabled Oticon hearing aids.
Full Story
~~~~~~~~~~~~~~~~~
January 2011
Directional-microphone technology has been used in
hearing instruments since the late 1960s, and has been shown to improve
speech understanding in background noise (e.g., see evidence-based review by
Bentler). For many years, this technology was considered a "special feature"
and was available only in select models. All this has changed in the last
15-20 years, and today manufacturers offer directional technology in most of
their hearing instruments. In modern instruments, the directional effect
usually is accomplished using two omnidirectional microphones, which Siemens
introduced with its dual-directional microphones ("TwinMic") in 1997.
Research with this new technology produced encouraging findings. In 2002,
Siemens was the first to add automatic-adaptive functionality to the polar
patterns of directional microphones. It was "automatic" in that, based on
the results of an analysis of the situation-detection system, the algorithm
"automatically" switched from omnidirectional to directional or back to
omnidirectional. It was "adaptive" in that the directivity was focused to
the front, but the null of the polar pattern could be steered to correspond
with the loudest sound from the rear hemisphere, which allowed for maximum
attenuation of background noise in this general region. Or, if a diffuse
noise field was detected, the adaptive algorithm would select the polar
pattern that provided the best directivity.
Full Story
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December 2010
Objective: The purpose of this study was to examine
speech recognition through hearing aids for seven telephone listening
conditions.
Design: Speech recognition scores were measured for
20 participants in six wireless routing transmission conditions and one
acoustic telephone condition. In the wireless conditions, the speech signal
was delivered to both ears simultaneously (bilateral speech) or to one ear
(unilateral speech). The effect of changing the noise level in the nontest
ear during unilateral conditions was also examined. Participants were fitted
with hearing aids using both nonoccluding and occluding dome ear tips.
Participants were seated in a room with background noise present and speech
was transmitted to the participants without additional noise.
Results: There was no effect of changing the noise
level in the nontest ear and no difference between unilateral wireless
routing and acoustic telephone listening. For wireless transmission,
bilateral presentation resulted in significantly better speech recognition
than unilateral presentation. Bilateral wireless conditions allowed for
significantly better recognition than the acoustic telephone condition for
participants fitted with occluding ear tips only.
Conclusion: Routing the signal to both hearing aids
resulted in significantly better speech recognition than unilateral signal
routing. Wireless signal routing was shown to be beneficial compared with
acoustic telephone listening and in some conditions resulted in the best
performance of all of the listening conditions evaluated. However, this
advantage was only evident when the signal was routed to both ears and when
hearing aid wearers were fitted with occluding domes. Therefore, it is
expected that the benefits of this new wireless streaming technology over
existing telephone coupling methods will be most evident clinically in
hearing aid wearers who require more limited venting than is typically used
in open canal fittings.
Source and Order Report
~~~~~~~~~~~~~~~~~
November 2010
The human auditory system, during the course of
evolution, has become attuned to the multi-dimensional cues of speech, as
well as sounds from the broader acoustic environment. To keep auditory
perception as intact as possible, for as many people as possible, and for as
long as possible, we optimize hearing aid signal processing to ensure
audibility while maximizing these naturally occurring cues. In this context,
keeping acoustic cues natural implies, among other things, the reproduction
of sound with a high bandwidth, maintaining the information conveyed by
onsets of words, syllables, and environmental sounds, and the detailed
amplitude fluctuations that constitute sounds. Other examples relate to
binaural cues, such as interaural time and level differences, head shadow,
or better-ear effects. These are used when locating sound sources and
segregating one source from another. It has been demonstrated that hearing
aid signal processing, including some forms of wide dynamic range
compression (WDRC), can greatly affect interaural level differences and
better-ear effects. Therefore, hearing aid signal processing should be
designed with this in mind.
Full Story
~~~~~~~~~~~~~~~~~
by Jason A. Galster, PhD, and Elizabeth A. Galster, AuD
November 2010
Professionals are fitting open-canal behind-the-ear
(BTE) hearing aids to more patients than ever before. This is reflected in
the growth of BTE hearing aid sales, which now account for 60% of all
hearing aids sold in the United States. Patients, in turn, experience
reduced occlusion and improved sound quality and comfort as a result of
these open-canal fittings.
Advancements in feedback suppression algorithms have
made many of these beneficial features possible. Despite the advancements,
professionals have undoubtedly noticed considerable variability in the
performance of feedback suppression systems across products and patients.
The observed variability in the performance of a feedback suppression
algorithm is expected due to several factors, including differences in
manufacturers' feedback suppression algorithms, patients' pinna and ear
canal geometries, venting effects, and prescribed gains.
In open-canal fittings, the ear canal acts as a
large vent, increasing acoustic leakage and increasing the difficulty of
managing feedback. In occluded fittings, feedback is typically restricted to
a range of high-frequencies, most often between 3,000 Hz and 5,000 Hz.
Compare this to the open-canal fitting configuration where the energy of the
acoustic leakage flattens and some peaks have shifted downward in frequency.
The management of increased acoustic leakage across a wider range of
frequencies makes feedback suppression in open-canal fittings more complex
and creates a challenging condition for feedback suppression algorithms.
Full
Story
~~~~~~~~~~~~~~~~~
by Francis Kuk, PhD, and Denise Keenan, MA
November 2010
It has been almost 5 years since Widex reintroduced
frequency transposition as an approach to regain audibility of the high
frequencies that are either unaidable or unreachable. Since the introduction
of the Audibility Extender (AE), we have conducted several studies using
adults and children as subjects to demonstrate its efficacy. In general, we
have demonstrated that the use of AE with optimally selected settings, when
paired with proper training and use of the device, yielded positive changes
in the wearer's identification of speech sounds, especially of voiceless and
fricative sounds. Such benefits were seen in both quiet and noise
conditions.
Results of our reported studies showed that
significant improvements in consonant identification scores occurred after
the subjects have worn the AE for 1-2 months. Speech identification scores
with the AE during the initial fit, although improved, were not
statistically different from the scores measured with the non-AE program.
Full Story
~~~~~~~~~~~~~~~~~
October 2010
It is commonly assumed that audio processing should
highly value the concept of fidelity. Fidelity, of course, refers to a
premise that output should be "true to the input" and the "hi fi" industry
has engaged in marketing wars over gradations of fidelity. Included in the
standard specifications that proclaim "high fidelity" credentials are wide,
smooth bandwidths and the lowest possible measures of non-linear distortion.
Although the fidelity principle is routinely violated in hearing aid
fittings by purposeful alterations to the frequency response pattern and the
dynamic relations of soft and loud sounds, there persists a widespread
avoidance of waveform peak clipping and the harmonic distortion that may
result. Curiously, though, it has been understood for over 60 years that
even severe peak clipping does very little to disrupt speech understanding.
The extensive investigations by JCR Licklider and others at the Harvard
Psycho-Acoustics Laboratory in the late 1940s showed quite clearly that even
drastic ("infinite") clipping caused negligible reductions in word
recognition.
Full Story
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September 2010
Because all speech needs to emanate from a vocal
tract that is between 15 cm. (child) and 19 cm. (large adult) in length, it
is no surprise that the long-term speech spectra are similar for a wide
range of languages. All speech is generated by a soft-walled, moist set of
tubes (oral and nasal cavities) and, although we have articulators (tongue,
soft palate, lips) that can move, there are limitations to what we can
generate. Byrne et al. studied the long-term speech spectra of a number of
languages and (expectedly) found almost identical spectra. The only
consistent difference they found was that males have more low-frequency
emphasis than females, which is directly related to the lower fundamental
frequencies of the male subjects. This consistency in the human vocal tract
has allowed us to use aspects of the long-term speech spectrum in hearing
aid fittings. Music, however, is quite different. Some forms have long-term
spectra that are similar to the long-term speech spectrum and others bear
little resemblance. Music can have significant low-frequency energy or none
at all. It can have low- or high-frequency spectral emphasis. It can be very
intense, and it can be very quiet. In short, the dynamic ranges and
bandwidths of musical instruments can be, and typically are, much different
and greater from those of speech.
Full Story
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September 2010
While concentrating our clinical efforts on the
perception of speech in many different environments, hearing healthcare
providers may sometimes overlook other signals, such as music, that may be
very meaningful to the patient. Because hearing instruments are designed to
focus on speech, music lovers and musicians are often disappointed by the
sound quality of music. Settings and electroacoustic characteristics of
hearing instruments may be ideal for speech signals, but not for music. As
a result, hearing instruments may react inappropriately when music is
present, since there are many acoustic differences between speech and music.
A hearing aid that has been optimized to handle music as an input should
have both software and hardware differences from other instruments. Bernafon
has developed Live Music Plus, a software program with a dedicated
combination of features for live music processing, which is available in its
Veras and Vérité 9 hearing instrument families. In this paper we will first
review some of the differences between music and speech signals. We will
then explore the four elements that make up Live Music Plus, and finally we
will report on the reactions of some professional musicians who have tried
hearing aids with this program.
Full Story
~~~~~~~~~~~~~~~~~
September 2010
For many people, listening to music is an important
part of life. Most often the music is recorded and played on a CD player,
the radio, the television, an mp3 player, or a computer. Listening to music
from such devices was long out of reach for hearing aid users. But recently,
the development of devices, such as the Oticon Streamer, that can send music
wirelessly to hearing aids enables people to enjoy listening to music
directly in their hearing aids with a good signal-to-noise ratio. However,
listening to music sent directly to hearing aids is not optimal.
Specifically, the sound image appears to be inside the listener's head. This
is referred to as "in-the-head locatedness."1 When the signal is the same at
both ears (monophonic), the listener perceives it as being in the middle of
his or her head. When the signal is stereophonic, the sound is perceived as
being on a line between the ears. By changing the level of the signal in
either ear, the sound can be moved between the ears. This is referred to as
"lateralization of the sound image."
Full Story
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August 2010
For the past two decades, amplification for patients
with sensorineural hearing loss (SNHL) has been driven by the concept of
wide dynamic range compression (WDRC). It has been known for many years that
a core characteristic of SNHL is the reduction in dynamic range. The amount
of "working space" within the auditory system (the range between threshold
and the uncomfortable loudness level, or UCL) is typically smaller than the
full range of speech signals that a person is likely to encounter throughout
the course of the day. The WDRC approach was developed to take a full range
of speech inputs-the softest parts of soft speech through the loudest parts
of loud speech-and place them within the remaining dynamic range of the
patient. Over the years, a variety of schemes have been developed to
calculate the appropriate gain required for different input levels in order
to achieve the goal of full audibility. Most of the attention in this effort
has been paid to determining aspects such as how can audibility be maximized
without having sound levels violate the patient's loudness tolerance, what
is the minimal amount of audibility required for understanding of an
on-going signal, and which frequency regions should be prioritized, etc. One
aspect that has received less attention is the timing parameters of a
compression system. The basic concept of compression is that the gain
applied to the signal is inversely proportional to the input level: when the
input level goes up, the gain decreases; when the input level drops again,
the gain goes back up. However, the response of compression systems is
typically not instantaneous. Typical input signals, especially speech, are
not of a uniform level. Therefore, "waiting periods"-commonly known as
attack and release times-are often built into the response patterns of
nonlinear circuitry.
Full Story
~~~~~~~~~~~~~~~~~
August 2010
Imagine two scenarios. In the first, you're a little
late driving in an unfamiliar city (without satellite navigation), and
you're on your way to an important meeting. In addition to looking for
street signs, you are struggling to read a map to help you find your way.
The heavy traffic is disturbing you. You accidentally miss your exit and
must determine a new route to your destination. You are frustrated, and it
takes a lot of mental effort to complete the task. By the time you arrive,
you're exhausted.
Now, imagine a second scenario. You're driving to
work along the same familiar route you take daily. Traffic is flowing
smoothly, and the trip is routine. While driving, you think about your
weekend plans. Suddenly, you realize you've arrived at work. You've driven
through the whole town without actually noticing how you were driving, and
you arrive precisely on time while expending little mental effort.
Obviously, a drive through a city can vary
significantly with regard to the amount of problem solving, precision,
focus, conscious processing of new information, and memorization required,
the amount of mental effort expended, and the amount of stress experienced.
The first scenario represents a process that involves significant effort,
problem solving, and mental resources. The second scenario involves
over-learned driving patterns that made the drive automatic and effortless
and required few mental resources.
The above examples are analogous to different
listening situations. Some listening situations appear effortless, while
others demand much greater effort to understand what is being said. We know
hearing-impaired people expend more listening effort in demanding listening
situations. Full
Story
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August 2010
Although the concept of frequency lowering has been
around for at least four decades, it has recently seen a resurgence as a
"hot topic" in amplification. In the past 2 years, it has been implemented
in products from major hearing aid manufacturers, including Phonak. The goal
of frequency lowering is to shift high-frequency sounds that cannot be
adequately amplified by a hearing aid or used by the corresponding region of
the cochlea to lower frequencies where the information can be better
amplified or used. In particular, the feature is expected to assist in
making available such important information as high-frequency speech sounds
(e.g., /s/, /f/, /?/) and frequencies between 2000 and 5000 Hz that are
uniquely shaped by the pinna, depending on their angle of origin, to assist
with front-back (F-B) discrimination.
Full Story
~~~~~~~~~~~~~~~~~
July 2010
When a technique has been around for some time it is
usually assumed to be mature. This might not be true, however, in the case
of wide dynamic range compression (WDRC). Compression is certainly seen as
the suitable compensation for loudness recruitment, but at that point the
agreement ends. In fact, Moore writes in an article on compression that the
"controversy continues about...whether it should be fast acting or slow
acting."1 Likewise, Bor et al. say about multichannel compression that "the
appropriate number of channels remains an unanswered question." Such
uncertainties suggest room for improvement. Indeed, improvements are
necessary if hearing instruments are to increase user satisfaction. And
improvements are also possible, as this article will show.
Full Story
~~~~~~~~~~~~~~~~~
April 2010
EHIMA and HIA have completed a study on future
Electromagnetic compatibility and Radio spectrum Matters (ERM); Hearing
Instrument RF Interference Analysis. This study was the work of two experts
within the RF field. Brian Copsey is from Europe and heads the ETSI working
group. Stephen Berger, from the USA, is an expert on RF and other FCC
matters. Our industry has committed considerable resources to protect our
products from mobile phone interference over the past decade. This report is
the start of a continued effort to create awareness of new interference
risks to our products, and it will be updated on an on-going basis. With
this surveillance activity, our industry can be better equipped to handle
the next interference issue that arises.
Full Story
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April 2010
Despite a long history of research and commercial
efforts,1 hearing aids with frequency-lowering algorithms have become
popular only recently. Their lack of commercial success may be attributed in
part to the immaturity of analog technology when these devices were
introduced such that artifacts were plentiful. But insufficient training
provided to the wearers of such devices, unrealistic expectations, and
inadequate means to evaluate their efficacy are equally important
contributors to the limited acceptance for this technology. Widex
re-introduced the concept of linear frequency transposition in its Inteo
hearing aid in 2006 under the name Audibility Extender.2 Since then, we have
explored various avenues to better understand how such a feature can be
fitted3,4 and its use facilitated.5 Just as important, we also studied (and
developed) research tools that may be optimal for evaluating such an
algorithm. Our effort led us to report on the efficacy of such an algorithm
in a simulated hearing loss,6 in an open-tube fitting,7 in children,8 and in
adults in quiet and in noise.9 We have learned that demonstrating the
efficacy of a frequency-lowering algorithm is not a straightforward matter.
We would like to share our experience in this paper.
Full Story
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March 2010
Six months ago, hearing-aid salesman Doug Gibson
decided to start pitching a new product to his customers: high-tech hearing
aids that connect wirelessly via Bluetooth technology to cell phones, iPods
and televisions. He wondered whether anyone would buy them. Many of his
customers are in their 70s or older, and some do not use cell phones, let
alone hands-free sets or MP3 players. Gibson found what other retailers are
beginning to see as a trend. Baby boomers just beginning to need hearing
aids are gravitating toward ones equipped to handle their gadgets, or
disguise the hearing aid as one of them. "They're pretty techie people, and
they all have Bluetooth in their cars. Most are in their 50s to early 70s,"
Gibson says. "Soon I think we're going to be seeing a lot more." Aging
boomers, because of their large numbers and willingness to pay for style and
comfort, are a target market for manufacturers. Increasingly, that goes for
medical devices, too.
Full Story
