Subject: Re: Sensimetrics' Headset Listening device From: Peter Lennox <peter(at)LENNOX01.FREESERVE.CO.UK> Date: Thu, 1 Apr 2004 21:08:31 +0100Am I right in thinking that a headset-type array cannot incorporate any of the pinnae filtering part of the HRTF? - isn't this particularly important for the speech-in-noise problem? Even using a capsule either side of the head, so that at least you have duplex components and so some of the hrtf would behave properly, surely the lack of pinnae effects would be serous? - sorry if this is a naive question. It just seems to me that ideally, a hearing aid would make up for amplitude-with frequency loss within the context of the HRTF - ideally, wouldn't one wish to exaggerate pinnae notches to make up for the loss, or is this simply not possible? regards ppl ----- Original Message ----- From: "Patrick Zurek" <pat(at)SENS.COM> To: <AUDITORY(at)LISTS.MCGILL.CA> Sent: 01 April 2004 18:33 Subject: Sensimetrics' Headset Listening device > Dear List, > > 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 > noise superior > 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, > 1646-1657), > did focus groups, and shopped it around to hearing aid manufacturers. > > There are several reasons why our headset device has not yet been > commercialized. > > 1) There was zero interest from hearing aid manufacturers. Their reason > was the belief that people (in sufficient numbers, of course) will not use > a device > 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 > informal contacts > with hearing aid users encouraged us. We felt (and still feel) that there > is enough > of a market for this device for someone to make a go of it. But you face > the question: > 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 > our sails. > 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 > reverberant conditions, > 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 > adaptive > array performance in everyday environments. The improvements that can be > achieved > 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 > switched between > 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 > the size/cosmetic > 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 > President > > Sensimetrics Corporation > 48 Grove St. > Somerville, MA 02144 > Tel: 617-625-0600 x237 > Fax: 617-625-6612 > email: pat(at)sens.com > > > > 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. > > > >Dan Freed > >Senior Engineer, Hearing Aid Research Lab > >House Ear Institute > >2100 W. Third St. > >Los Angeles, CA 90057 USA > >Phone: +1-213-353-7084 > >Fax: +1-213-413-0950 > >Email: dfreed(at)hei.org > > > > > >-----Original Message----- > >From: AUDITORY Research in Auditory Perception > >[mailto:AUDITORY(at)LISTS.MCGILL.CA]On Behalf Of Maher, Rob > >Sent: Wednesday, March 31, 2004 2:56 PM > >To: AUDITORY(at)LISTS.MCGILL.CA > >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 > >market? > > > >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!). > > > >Rob Maher > >Associate Professor of Electrical and Computer Engineering > >Montana State University-Bozeman > >rob.maher(at)montana.edu > > > > > >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 > >...