Hearing Aid Research and Technology
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.
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 2004 - Are your hearing aids bluetooth-enabled? Would you like
them to be? It's not as hard as you think; anyone who's reasonably handy
with a soldering iron can build a hearing aid
bluetooth adapter!
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!
January 2006 - The Future of Wireless Devices in
Hearing Health Care
July 2006 - ASU Pursues High Tech Hearing Loss
Solutions
August 2006 - The History of Hearing Aid
Technology
October 2006 - Here's Mark Ross with a
great article on Feedback Cancellation Systems and Open-Ear Hearing Aid
Fitting.
October 2006 - Rechargeable
Hearing Aids
March
2007 - Binaural Processing in Hearing Aids?
April
2007 - Oticon
Epoq wireless capabilities provide binaural processing and more
April
2007 - Hearing Aids and Hi-Tech Devices Converging
April 2007 - Trainable,
self-adjusting hearing aid in the works
April
2007 - Adjusting Hearing Aid Compression Algorithms
May 2007 - Hearing and Cognition: Cutting
Edge Hearing Aid Research
May 2007 - Wirear - a
HiTech and Stylish Hearing Aid
May 2007 - Binaural Hearing Aid Processing
Promises Improved Performance
May 2007 - Hearing Aid Technology: Past,
Present, and Future
June 2007 - Fly's
Ear Inspires New Hearing Aid Microphone
June 2007 -
Hearing Aids and Wireless Technology
Sept 2007 -
Why Don't Directional Microphones Work Better?
October 2007 -
Hi-Tech Devices Communicate with Hearing Aids
October 2007 -
RI Company Working on Revolutionary Hearing Aid
December 2007 -
Binaural sharing of audio signals; Prospective
benefits and limitations
December 2007 -
Wireless transmission of speech and data to, from, and
between hearing aids
December 2007 -
Hearing Aids and Wireless Protocols
December 2007 -
Assessing the feasibility of
Bluetooth in hearing rehabilitation
March 2008 -
Using Nanotechnology and Nanoparticles to Improve
Hearing
June 2008 -
SoundRecover- A Breakthrough in Enhancing
Intelligibility
June 2008 -
Here's the OSPA High Tech Hearing Aid
July 2008 - IntriCon Unveils New
High-Performance DSP Hearing Aid Amplifier
November 2008 - How Hearing Aids May Be Set for
Different Languages
November 2008 - Understanding Hearing Aid Technology
December 2008 -
New discovery leading towards intelligent hearing aids
December 2008 -
Comparison of Three Premium Products: Does Design
Philosophy Matter?
January 2009 -
Bluetooth and Hearing Aids: Ready for
prime time?
January 2009 -
Re-evaluating the Efficacy of Frequency
Transposition
February 2009 - Audigence, Audina and UF Team to
Improve Hearing Aid Performance
February 2009 -
The Next Big Thing in Hearing Aid Technology
March 2009 - Multicore processor powers hearing aid
April 2009 - Frequency-lowering Hearing Aids:
Increasing the audibility of high-frequency speech sounds
April 2009 -
Binaural hearing on the telephone
with Bluetooth
May 2009 - Environmentally Adaptive Hearing Aids
May 2009 - What's next in hearing instrument
technology?
June 2009 -
Starkey Labs makes hearing aid controlled by cell
phone
August 2009 - New Software Promises Better Speech
Recognition for Hearing Aids and Cochlear Implants
August 2009 - New Hearing Aid Software Improves
Speech Recognition
September 2009 - How good is the typical hearing aid
fitting?
October 2009 - Programming hearing aids using speech
rather than beeps!
October 2009 - Real-world benefit from directional
microphone hearing aids
March 2010 - Boomers Demanding More Technology in
Hearing Aids
April 2010 - HIA and EHIMA Partner on HA Interference
Study
April 2010 - Interpreting the efficacy of
frequency-lowering algorithms
May 2010 - 3-D imaging technology
could lead to hearing aids that fit better
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
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
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
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
October 2010 -
Some Comments on Hearing Aid Features
October 2010 -
Peak clipping revisited: Turning distortion to
listener advantage
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
December 2010 - When your hearing aid gets wet
December 2010 - Comparison of Wireless and Acoustic
Hearing Aid-Based Telephone Listening Strategies
January 2011 - New algorithm automatically adjusts
directional system for special situations
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
April 2011 -
Siemens Introduces New Products Including
Waterproof Hearing Aid
April 2011 -
New Hearing Aid Has Microphone in Ear Canal
June 2011 - Audiotoniq Announces
Revolutionary High-Tech Hearing System
June 2011 - Siemens Releases Waterproof,
Dustproof, Shock-Resistant Hearing Aid
July 2011 -
ReSound Releases Dual-Microphone Wind Noise
Reduction Technology
August 2011 - Hearing aids running on
methanol
August 2011 - Digital Wireless
Hearing Aids, Part 3: Audiological Benefits
September 2011 -
Phone and TV Solutions for Better
Hearing
October 2011 -
Understanding the Terms "Water Resistant" and
"Waterproof"
November 2011 - Solar Ear CEO Named Social
Entrepreneur of the Year
December 2011 - Panasonic Expands on
Hearing Instrument Lineup
December 2011 -
Digital Wireless Hearing Aids, Part 4: Interference
January 2012 -
Programming hi HealthInnovations'
Hearing Devices
January 2012 - Bringing
Rechargeable Hearing Aids into the Mainstream Market
More on this and related
topics
~~~~~~~~~~~~~~~~~
October
2006
We
recently published an article about a hearing aid with rechargeable
batteries that was intended for countries where frequent battery
replacement is impractical. At the time I was wondering why there are no
rechargeable hearing aids available in the United States. Well, it turns
out there are! Magnatone has had a rechargeable hearing aid available for
some time (http://www.magnatone.com/liberty.html),
and Resound has just announced theirs (http://www.resoundpulse.com).
It sure makes a lot of sense to me. I wonder if others will follow suit!
~~~~~~~~~~~~~~~~~
April 2007
Thanks to the rise of wireless technology, the Rodney
Dangerfield of the gadget world is about to get a makeover. The humble
hearing aid, long shunned by engineers as a technological dinosaur, is
going stereo and getting linked to cell phones and MP3 players, moves that
could turn this badge of old age into a gizmo with the cachet of a
Bluetooth ear clip. The transition will be no flash dance. Hearing aids
have frustratingly restrictive size and power requirements that make most
wireless technologies nonstarters, and public perceptions are slow to
change. Indeed, only one in five people with significant hearing loss in
the United States and Europe actually uses a hearing aid, in part because
the devices are perceived as granny accessories. What's more, the
regulatory environment is somewhat confusing and is currently more focused
on problems of wireless interference than on interoperability. Full
Story
~~~~~~~~~~~~~~~~~
April
2007
Recently,
the concept of a "trainable" or "self-adjustable"
hearing aid was introduced.1 In brief, the trainable hearing aid presents
the user with a set of control buttons that are used to manually adjust
selected hearing aid parameters to reach the user's preferred gain and
frequency response. Using the control buttons, the user can adjust the
device to his or her own listening preferences outside the clinic in a
variety of everyday acoustic environments. During this process, the
hearing aid identifies the acoustic characteristics of the environment and
combines this data with manually input information about the user's
preferred gain and frequency response. When sufficient data have been
accumulated, the hearing aid begins to make predictions about the user's
preferences in different listening situations based on the environment's
acoustic characteristics, and continues to refine these predictions for as
long as additional input from the user is received. The device is
considered "fully trained" when the hearing aid is able to
accurately predict the user's listening preferences in different acoustic
environments and therefore no longer requires manual adjustments on the
part of the user. Full
Story
~~~~~~~~~~~~~~~~~
April 2007
Amplitude compression was proposed as an
amplification strategy over 50 years ago, and has been widely used in
hearing aids for 15 years (Dreschler, 1992). Nearly 300 research studies
have been published on the use of compression. (Simply perform a Pub Med
Search (www.ncbi.nlm.nih.gov) on the keywords “hearing aid
compression”.) Despite the number of studies, clinicians continue to
have questions about choosing the optimal compression parameters for
patient needs and how to make compression adjustments in response to
patient complaints. The confusion is partly because compression is so
complex. In digital hearing aids, clinicians can adjust one or more
compression thresholds, compression ratio, attack and time release time in
each channel, plus expansion parameters, in addition to adjusting gain,
output, crossover frequencies and maximum output. Additionally, the
“first fit” option in many digital hearing aid systems tends to hide
the access to many of the more advanced parameters in the fitting
software. No wonder adjusting a hearing aid is not always straightforward!
Full
Story
~~~~~~~~~~~~~~~~~
May 2007
The long-established protocols for testing the
effectiveness of hearing aids are changing as researchers seek to remedy
the relationship between hearing impairment and cognitive development. The
findings of the latest research in hearing science are intriguing. The
potential outcome – the development of a multi-dimensional hearing
device designed to not only improve the wearers’ ability to hear, but to
also improve the ability to understand. Full
Story
~~~~~~~~~~~~~~~~~
May 2007
Epoq is the first hearing instrument built on
Oticon's RISE platform. This architecture was designed with connectivity
as a core design feature. Incorporating earStream processing,
communication between devices occurs at broadband speed. The Epoq hearing
instruments can then work together, becoming one central processing unit.
Going beyond simple binaural volume control and programming shifts,
earStream technology allows the hearing instruments to share information
at previously unseen speeds. Binaural signal processing algorithms that
provide the user with a more natural and truer soundscape can be
implemented. Full
Story
~~~~~~~~~~~~~~~~~
May 2007
This article will discuss how advances in
semiconductor technology have enabled hearing aid manufacturers to reduce
the size and the power consumption of their products. It will also explain
why ultra-low-power semiconductor technology technology alone is no longer
sufficient to enable the highly sophisticated hearing aids of today that
require entire minicomputer systems on a piece of silicon. These systems
must be flexible so they can be quickly reconfigured to enable new feature
sets for hearing aids, and they need to be closely mapped to the
semiconductor technology they use to optimize performance. The article
will then discuss how semiconductor companies have crafted such systems,
first by introducing digital signal processing (DSP) technology and now
reconfigurable DSP systems. It will conclude with a short discussion of
hearing aid features that enable today’s technology, new features that
may soon become available, and an example of an advanced new hearing aid
IC (integrated circuit). But first, let’s take a brief look at the
history of the hearing aid. Full
Story
~~~~~~~~~~~~~~~~~
June
2007
Now,
acoustic engineer Ron Miles, Ph.D., of Binghamton University in New York,
has developed a new, directional hearing aid inspired by flies. "The
fly turns out to have some pretty interesting mechanical structures that
enables it to respond differently when sounds come from different
directions, so we're trying to mimic that basic idea," he said. Dr.
Miles' new hearing aid contains a tiny microphone modeled after a fly's
ear that works like a teeter-totter. "So when sound comes from this
direction, it rocks, but if a sound came form this direction, it wouldn't
rock," he said. Full
Story
~~~~~~~~~~~~~~~~~
June 2007
Poor performance in noise is also given as a primary
reason for nonadoption [of hearing aids]. This opinion is sometimes based on
personal experience and sometimes on negative reports by disappointed
hearing aid users in the social network.4 An additional, related complaint
is inability to hear distributed speech in public places such as museums,
theaters, lecture halls, and places of worship. Wireless technology offers
a proven solution to these problems and may have other applications that
improve the effectiveness and acceptability of hearing aids. The purpose of
this paper is to review existing and potential wireless applications and to
outline needs for the future.
http://tinyurl.com/3cknxo
~~~~~~~~~~~~~~~~~
September 2007
It is common knowledge to hearing health care
professionals that individuals with hearing impairment have a great deal of
difficulty understanding speech in the presence of background noise, even
with appropriately fitted hearing aids. This was especially true when
hearing aids consisted of linear amplifiers that tended to degrade speech
when embedded in background noise due to "distortion, narrow bandwidth,
irregular response, and inappropriately adjusted (or available) frequency
response." Since the advent of both digital signal processing (DSP) and
directional microphone systems, hearing aid manufacturers and dispensing
professionals are sometimes tempted to make claims that, in aggregate, give
the consumer the impression that these systems can normalize hearing and
make communication in noisy situations an easy task. While directional
microphone systems, when partnered with DSP, do appear to be a great benefit
to hearing aid users confronted with background noise, it is important to
understand both the potential benefits and continuing limitations of these
technologies.
Full Story
~~~~~~~~~~~~~~~~~
October 2007
When Evanston business executive Neil Gambow gets a
call on his cell phone, he hears the voice on the other end directly through
his hearing aid. Gambow, 61, wears the Epoq, a high-tech hearing aid that
integrates wireless and Bluetooth connectivity. 'The opportunity to have
sound transmitted directly into my ears was compelling,' said Gambow,
explaining why he purchased the Epoq over the summer after wearing
traditional hearing aids for the last 12 years. 'I've gone for a walk and
used it with an MP3 player.' Hearing aids have come a long way since the
1800s, when the only listening device available was a weird-looking metal
contraption called an ear trumpet. Today about 1.7 million hearing aids are
sold in the U.S. each year, and they're not just for clarity of hearing
anymore. Now they plug people in to the digital revolution. The Epoq
connects to a cell phone, MP3 player, radio or personal computer via a
Streamer, a remote-control-type device that resembles an iPod. The Streamer
acts as a receiver and transmitter, giving the hearing-aid wearer the
equivalent of a hands-free Bluetooth headset.
Full Story
~~~~~~~~~~~~~~~~~
October 2007
Bionica Corp. has filed for eight patents related to
the Clio, a hearing aid it is developing in a Jewelry District loft. The
small company, financed in part by The Slater Technology Fund, has resisted
disclosing many aspects of its technology. But after completing the patent
filings, Bionica's chief executive officer, Peter T. Hahn, offered some
general design details for the first time. The Clio's controls are simple to
operate, modeled after popular digital music players, Hahn said in an
interview. The acoustic feedback triggered by many hearing aides, he said,
was eliminated by separating the microphone from the speaker. A "very
powerful" microprocessor, specially designed software and a strategic
microphone array will help distinguish between speech and background noise,
Hahn said. The Clio has also been built to adapt to various settings, with
special software "programs" designed to interpret door bells, house alarms
and TVs. Different programs will activate different microphones depending on
the situation, according to the company, founded two years ago. Users will
be able to scroll through a menu of the programs using a hand-held device
that Bionica compares to an Apple iPhone. It will contain a radio frequency
module that communicates with an earpiece.
Full Story
~~~~~~~~~~~~~~~~~
December 2007
We've recently started seeing communications between
a person's two hearing aids. Devices like the Oticon Epoq allow the aids to
communicate control signals, such as gain settings. This technology has some
potential to improve hearing aid performance for users, but the real benefit
will likely come with the communication of audio information between hearing
aid. But there are some issues to be worked out along the way. Here's a
pretty good discussion of this topic.
Full Story
~~~~~~~~~~~~~~~~~
March 2008
Officials of NanoBioMagnetics, Inc., (NBMI) have
announced the issuance of its first patent by the U.S. Patent and Trademark
Office. The patent, titled "Method and Apparatus for Improving Hearing," is
based on the use of magnetically responsive nanoparticles implanted in the
organs of the middle ear to drive tissue vibrations in the amplification of
sound. The technology was the first demonstration of the nanomechanical
movement of tissue and operates in principle much like a typical commercial
electromagnetic hearing aid. Development and validation was done during
2002 - 2004. The company now will move the technology through
commercialization partnerships. Statistics of the National Institutes of
Health indicate sensorineural hearing loss affects approximately 28 million
Americans. The technology covered by today's patent has the potential to
move hearing aid systems to smaller and totally implantable hearing devices,
achieving more favorable patient economics performance and compliance.
Full
Story
~~~~~~~~~~~~~~~~~
June 2008
Phonak, in collaboration with the University of
Melbourne, developed SoundRecover, an innovative non-linear frequency
compression algorithm. It compresses selected high frequency sounds into a
lower frequency range where both hearing sensitivity and discrimination
ability are better. The proprietary algorithm effectively extends the
audible range without creating any annoying artifacts. Frequencies below the
compression knee point are amplified conventionally while only the high
frequencies are compressed. The initial frequency compression setting is
automatically calculated by the fitting software for each wearer and can be
easily fine tuned if needed. Many hearing impaired people with poor high
frequency discrimination will benefit from the intelligent SoundRecover
algorithm.
Full Story
~~~~~~~~~~~~~~~~~
June 2008
The latest offering from innovative industrial
design team think/thing is the OSPA (Optical Speckle-Pattern Analysis), a
unique hearing aid which is non-invasive, has a visually attractive design
and uses a process called speckle-pattern analysis to read vibrations and
produce sound . . . . OSPA is not designed to be hidden from sight, in fact
with its streamlined, elegant, magnesium frame it looks more like a fashion
accessory. However there is function within that frame, OSPA uses lasers and
optics to read mechanical vibrations and has the potential to provide
well-balanced, natural and high resolution sound. Unlike other hearing aids
which use a microphone and speaker to amplify sound, OSPA uses bone
conduction to transmit sound to the the inner ear. When a sound signal is
received by the external ear, an optical sensor picks up the vibrations of
the ear drum, reconstructs the sound and sends it to the ear bud via an
optical fiber.
Full Story
~~~~~~~~~~~~~~~~~
November 2008
There is no inherent reason why the vocal output of
an English speaker should be any different from a person speaking Chinese.
However, the SII (and AI) are based on which sounds are linguistically
distinctive or important in that language. The frequency band importance of
a Chinese speaker has greater value in the lower frequencies than for
English because Chinese relies more on pitch changes in the lower-frequency
vowels. This article explores possible programming considerations related to
different languages.
Full Story
~~~~~~~~~~~~~~~~~
November 2008
If you wear a hearing aid or are thinking about
getting one, you are probably confused about the terminology concerning
hearing aids. Hearing aids are very complicated and are essentially
computers sitting in or behind your ear. This is a 3 part story on the basic
terminology of hearing aids. I hope this helps you make an informed decision
about which hearing aid is right for you.
Full Story
~~~~~~~~~~~~~~~~~
December 2008
Digital signal processing (DSP) technology has had
15 years to evolve within the hearing instrument industry. We have reached
the point where creative new algorithm features are being released as often
as every 6 months. Historic hardware limitations, such as high battery
consumption and limited processing power, no longer completely define the
boundaries of what is possible. Hearing instruments are more often
differentiated on the basis of software algorithms rather than hardware
platforms. Thus, the algorithms that a manufacturer designs today to
differentiate its products are dictated more by the company's philosophy
than by technological restrictions. One could argue that there is little
evidence that individual differences in features yield measurable
performance effects.1-3 However, it may also be true that the whole of a
hearing instrument is greater than the sum of its features. That whole is
what is determined by the fitting philosophy of its developers. Thus, if the
developer's design philosophy can effect performance improvements, then
hearing aids based on widely different design philosophies should
demonstrate discernable differences in performance.
Full Story
~~~~~~~~~~~~~~~~~
January 2009
Patients with a precipitous high-frequency hearing
loss pose a unique challenge for dispensing audiologists. Hearing aids
rarely provide sufficient high-frequency gain without over-amplifying the
lower frequencies, which results in poor sound quality or significant sound
distortions. The occlusion effect and upward spread of masking may also
occur. For these patients, the high frequencies are not easily reachable.
Recently it has been suggested that a precipitous loss may make the high
frequencies non-functional, "dead," or unaidable. Some studies suggest a
decrease in word recognition scores when these "dead" regions are amplified.
This result casts doubt on the usefulness of amplifying such a region. For
people with either an unaidable or unreachable high-frequency hearing loss,
information carried in those frequency regions would not be available
despite the use of amplification. Audibility of unaidable or unreachable
high-frequency information is achieved by converting that information to the
lower frequencies where hearing is aidable or reachable. This conversion
process is called frequency lowering. For example, information carried at
4000 Hz may be "lowered" to 2000 Hz so that it is heard as 2000 Hz. It is
important to recognize that frequency lowering doesn't restore hearing in
the original high frequencies. Instead, the signals are heard at a lower
frequency. For this reason, a frequency-lowered signal will initially sound
"unnatural" to most listeners.
Full Story
~~~~~~~~~~~~~~~~~
February 2009
SMAKA: Can you begin by giving us an overview of the
research department at Starkey?
EDWARDS: Sure. We have significant efforts in
research here in Berkeley and also in Minnesota. The center here in Berkeley
opened four years ago, and was created to initially focus on basic auditory
perceptual science questions. At Starkey, we feel that in order to achieve
the next advances in technology that benefit those with hearing loss, we
need to go back to a basic understanding of more complex aspects of auditory
perception. Over the past several years with digital technology, we've
captured a lot of the low-hanging fruit in terms of benefit, for example,
with directional technology, noise reduction, etc. But to really understand
the potential of new technologies, for example, ear-to-ear wireless
technology, or to explore other areas of benefit for the hearing impaired,
we need to better understand the complexities of auditory perception.
Full Story
~~~~~~~~~~~~~~~~~
March 2009
A technology licensing company is in the final
design stages of a novel hearing aid it says could be sold over the counter
for as little as $100. The low cost but powerful device is based on the
company's homegrown multicore processor and audio algorithms. The behind the
ear device can be customized by the user on a standard PC. It performs as
well as top-end $3,000 devices that fit inside the ear canal and require
insertion and tuning by an audiologist, the company claims.
Full Story
~~~~~~~~~~~~~~~~~
June 2009
STOCKPORT-based hearing manufacturer Starkey
Laboratories has developed technology that allows hearing aid users to
control their devices with a mobile phone. The T2 technology is a feature of
the company's new S Series hearing device, which allows a touch tone
telephone to adjust volume, to switch memory settings or to mute the hearing
aid. The company said the product will help users who can often feel
self-conscious when having to manually adjust a switch on their aid, or use
a separate remote control to change settings.
Full Story
~~~~~~~~~~~~~~~~~
September 2009
Hearing aid verification and validation may be
underutilized, according to recent surveys of dispensing audiologists
(Strom, 2006) and ASHA-certified audiologists (ASHA, 2008). Hearing aid
verification is the process of confirming prescribed electroacoustic
performance of hearing aids, usually gain and maximum output, in the
wearer's ear; validation is the process of confirming the benefits provided
by amplification to the wearer.
Full Story
~~~~~~~~~~~~~~~~~
October 2009
This article summarizes data from a 3-year,
double-blinded study of directional hearing aid benefit. Ninety-four
subjects in three hearing loss groups, all previous users of omnidirectional
output-compression hearing aids, completed all aspects of the study.
Participants were fit with new hearing aids for 1 month in a directional
mode and 1 month in an omnidirectional mode. Following 1 month of use,
subjects completed a number of objective and subjective measures of hearing
aid outcome. Objective and subjective data were analyzed across hearing aid
and hearing loss conditions. Subjects in all hearing loss groups exhibited
better performance in the directional conditions for objective
speech-in-noise measures; however, subjective data did not indicate a clear
advantage for directional amplification. Results and clinical implications
are discussed.
Full Story
~~~~~~~~~~~~~~~~~
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
~~~~~~~~~~~~~~~~~
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
~~~~~~~~~~~~~~~~~
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
~~~~~~~~~~~~~~~~~
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
~~~~~~~~~~~~~~~~~
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
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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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Full Story
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
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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
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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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Peak clipping revisited: Turning distortion to listener
advantage
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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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
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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
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by Francis Kuk, PhD, and Denise Keenan, MA
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
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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
~~~~~~~~~~~~~~~~~
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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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
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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
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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
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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
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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
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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
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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
