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Sensimetrics' Headset Listening device
Dan Freed is right. We did have a project here at Sensimetrics to develop
a headset-style assistive-listening device. Because the recent discussion
of Killion and Gudmundsen's initiative for OTC sale of some types of
hearing aids has
turned to ways of enhancing hearing-aid performance, I'll give you a
summary of our
experience, which touches both of these topics.
The headset design was motivated mainly by the improved performance in noise
that could be achieved from a microphone array mounted on the headband.
Other advantages were that it could be mass-produced (because it used
non-custom insert earphones), it had large controls for easier use by
elderly fingers, it's larger size could accommodate a larger battery and
more advanced electronics, and it looked like a personal stereo, not a
hearing aid, which we hoped could mitigate stigma. We estimated that such a
device, giving high-quality binaural amplification with performance in
to ear-level aids, could be made and sold at retail for less than $1,000.
We made the argument that this device in relation to hearing aids could be
analogous to eyeglasses in relation to contact lenses -- a larger but
more-comfortable device that's easily removed, used mainly at home, etc.
We made many prototypes, with both fixed and adaptive processing,
evaluated speech-in-noise performance (Greenberg et al. (2003) JASA,113,
did focus groups, and shopped it around to hearing aid manufacturers.
There are several reasons why our headset device has not yet been
1) There was zero interest from hearing aid manufacturers. Their reason
was the belief that people (in sufficient numbers, of course) will not use
that is highly visible. As evidence they point to: the increased use of
smaller, less-visible hearing aids; Starkey's experience with their
"Radiant Beam" necklace array product; and the relatively low prominence
of (interpreted as low-demand for) assistive listening devices
generally in the hearing-device market.
2) The second problem is the distribution channel. Our focus groups and
with hearing aid users encouraged us. We felt (and still feel) that there
of a market for this device for someone to make a go of it. But you face
where will such a device be sold? Because it is not a hearing aid there
would be no
restraint on selling it over the counter. But at what outlet? It's hard to
picture, say, a
$500 listening device being sold at a drug store, or through mail order. It
would have to be sold
through hearing aid dispensers. But for a variety of probable reasons,
dispensers as a group
have tended not to promote assistive listening devices. To go forward with
this device commercially
would require a huge educational effort.
3) The third reason is that our own research findings took some wind out of
We knew for many years, based on lab studies (Greenberg and Zurek, JASA 1992),
that reverberation will ultimately limit the noise-reduction performance of
adaptive microphone arrays. But without an "environmental survey" of
we did not not know how severe that limit would be. In recent work (with
Jay Desloge and
Martin Zimmer, which we'll report at the ASA in May) we've taken a look at
array performance in everyday environments. The improvements that can be
by a two-mic array (1-cm spacing) are very small (1-2 dB) compared to a
simple cardioid mic.
This can be experienced directly by using a portable processor that can be
adaptive and fixed algorithms; it's hard to find realistic noise-source
distances where you can
hear much difference. If the headset device then is effectively only a
fixed array, you have to
compare the performance of it to binaural cardioid microphones, which can
be used on traditional
ear-level aids. The difference in directivity between a 4-mic headset array
and a cardioid mic
is again pretty small (without factoring in the binaural advantages that
accrue from a
pair of cardioids).
What we've learned is that it's very difficult to make
objectively-verifiable progress on the
speech-in-noise problem in real-world acoustic conditions. The gains that
can be made
available in hearing assistive devices are likely to require compromises in
dimension, which people are currently reluctant to make. But I don't agree
with Dan Freed
that the stigma of hearing aids is un-changeable. It's only an attitude,
and attitudes can be changed.
Patrick M. Zurek
48 Grove St.
Somerville, MA 02144
Tel: 617-625-0600 x237
At 06:47 PM 3/31/2004, Freed, Dan wrote:
I recall reading a description of a headset-style hearing aid on the
website of Sensimetrics (www.sens.com). I believe it was developed by Pat
Zurek. If I remember correctly, the electronics were contained within the
headband, so no body-worn processor was required. I notice that the
website doesn't mention it anymore. Is there anybody out there from
Sensimetrics who can provide more information?
I think that hearing aids will always carry more stigma than eyeglasses,
even if they work perfectly, because hearing loss is so strongly
associated with aging.
Senior Engineer, Hearing Aid Research Lab
House Ear Institute
2100 W. Third St.
Los Angeles, CA 90057 USA
From: AUDITORY Research in Auditory Perception
[mailto:AUDITORY@LISTS.MCGILL.CA]On Behalf Of Maher, Rob
Sent: Wednesday, March 31, 2004 2:56 PM
Subject: Re: Hearing aid owner dissatisfaction
After seeing that (1) and (2) are related to hearing aid performance, I
wonder if there has been any research comparing the true potential
available benefit from a high performance signal processing system vs. the
market-driven low-power BTE and ITE hearing instruments.
Specifically, I have a hunch that better performance might be available
using off-the-shelf signal processing elements rather than trying to make
everything fit in a thimble and run on 1.2V. The user might then be able to
tune the device using training sessions on a PC. Are there laboratory
research systems that give users more benefit than what is available on the
The anecdotes I hear are that users wouldn't mind wearing a Walkman-style
headset and belt-mounted processor if the hearing aid actually provided
sufficient benefit. The tacit reason users want hidden devices is that they
don't really work too well and therefore people are embarrassed to be seen
as "impaired". We seem to have overcome the social stigma of eyeglasses
(arguably because they work!).
Associate Professor of Electrical and Computer Engineering
Montana State University-Bozeman
Brent Edwards wrote:
> From an article published in 2000 on the hearing aid in the drawer
> phenomenon, the top 20 reasons why hearing aid owners don't use their
> hearing aids are:
> 1. Poor benefit
> 2. Background noise/noisy situations