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Re: [AUDITORY] National Hearing Test

Hi Dick:

Your questions are, as usual, 'spot on' and in tune with my way of thinking.

While there is evidence (some of it highlighted by Pierre and Bill) of degraded performance at high levels for normal hearing listeners, I would argue that the degradation is comparatively less for normal-hearing listeners than for hearing-impaired listeners, even though as you said normal-hearing and hearing-impaired listeners share common cochlear mechanical properties at high levels. Also, a paper just published (Gregan et al. 2013 JASA) suggests little correlation between residual compression and masking release. Therefore, I think that reduced compression and broader filters can explain only a (small) part of the difficulty experienced by hearing-impaired at understanding speech in noise. The question is what explains the other (larger) part. I think the answer is 'deafferentation'.

We know that age is a separate contributor to degraded performance in noise that adds on to hearing impairment. This is beautifully shown by Table I of Peters et al. (1998, JASA 103:577-587). What I find most interesting, however, is that age leads to auditory nerve deafferentation (Makary et al. 2011, JARO) and deafferentation also occurs after noise exposure (see Kujawa and Liberman 2009) even in clinically-normal individuals. Therefore, it is very likely that deafferentation occurs even more frequently and significantly for hearing-impaired individuals. We have recently shown (Lopez-Poveda and Barrios 2013 Front. Neurosci.) that degradation of the acoustic signal inspired by deafferentation can impair speech intelligibility in noise but much less so in quiet without altering audiometric thresholds. Altogether, this makes me think that deafferentation is a common, underlying cause of degraded peformance in noise for both hearing-impaired listeners and (audiometrically-normal) aged listeners. What is more, I would dare saying that deafferentation degrades performance in noise more than does reduced frequency selectivity (broader filters) and/or reduced compression. The mechanism of how deafferentation would degrade performance in noise is described in our paper (Lopez-Poveda and Barrios 2013 Front. Neurosci.).

That's my current thinking, anyhow, and here are some relevant references:



- Enrique

El 04/11/2013 21:13, Bill Woods escribió:

Hi Dick,


One of your questions is easy to answer. Even listeners with normal hearing show decreased intelligibility at constant SNR as overall level is raised. Fletcher and his group saw this in their work, and Studebaker et al. (1999) provide a more recent set of data on this. I’ve seen different arguments for why this might be the case but I’m not sure it’s completely understood. Arguments would include processes such as changing filter bandwidth, changing compression amounts, and changing saturation of nerve fibers as level is changed. (Judy Dubno’s group has also been looking at this more recently.)


As Pierre mentioned in an earlier post, Judy Dubno and Larry Humes have done a great deal of work in the area of understanding speech performance with aging and hearing loss, and they have a very nice review chapter in a 2010 Springer book, “The Aging Auditory System”. I’d say their chapter is a great place to start if you want to get a good overview of the current state.


One main issue Dubno and Humes (2010) point out is that basic audibility accounting (using articulation index) goes a long way in capturing a large portion of the variance of speech performance across listeners. From this perspective, one way in which the phone test results may yield correlation with absolute thresholds is if the noise used is not above absolute threshold in some important speech frequency region (I assume the noise level is constant and the speech level is adapted in the phone test, as in the Dutch version). When this is the case, absolute threshold itself, and not the noise, will be contributing to the speech level required for 50% correct, thus increasing correlation with pure tone average (PTA) directly.


Audibility alone doesn’t always capture all the variance, however, and there is ongoing research looking to understand the influence of other contributors, such as reduced inner hair cell and/or auditory nerve fiber count, which may manifest as poor performance on basic, supra-threshold auditory tasks such as frequency modulation detection (see, e.g., Strelcyk and Dau, 2009). Note that these other contributors may affect speech performance in quiet as well as in noise (see, e.g., our 2013 paper on a related issue).


In the end, the health of many of the processes contributing to speech intelligibility performance in quiet and in noise may all be correlated with age to some degree, and thus also correlated with each other. It would be interesting to hear from the Phone Test folks how much variance in predicted PTA is reduced (or how much categorization into their three categories is improved) when the phone test results are added to predictions based on age alone.



Bill Woods

Starkey Hearing Research Center

Berkeley, CA


Humes, L. E., and Dubno, J. R. (2010). “Factors affecting speech understanding in older adults,” in The Aging Auditory System, edited by S. Gordon-Salant, R. D. Frisina, A. N. Popper, and R. R. Fay (Springer, New York), pp. 211–257.


Strelcyk, O., and Dau, T. (2009). “Relations between frequency selectivity, temporal fine-structure processing, and speech reception in impaired hearing,” J. Acoust. Soc. Am. 125, 3328–3345.


Studebaker, G. A., Sherbecoe, R. L., McDaniel, D. M., and Gwaltney, C. A. (1999). “Monosyllabic word recognition at higher-than-normal speech and noise levels,” J. Acoust. Soc. Am. 105, 2431–2444.


Woods, W., Kalluri S., Pentony S., and Nooraei, N. (2013). “Predicting the effect of hearing loss and audibility on amplified speech reception in a multi-talker listening scenario,” J. Acoust. Soc. Am. 133, 4268–4278.





From: AUDITORY - Research in Auditory Perception [mailto:AUDITORY@xxxxxxxxxxxxxxx] On Behalf Of Richard F. Lyon
Sent: Thursday, October 31, 2013 11:21 AM
To: AUDITORY@xxxxxxxxxxxxxxx
Subject: Re: National Hearing Test


I took the test just now and got the expected result:  "slightly below normal range" in both ears (expected, based on previous tests that show somewhat worse than typical hearing for my 61-year age).

It would be great if there was better quantification of the result, like dB of SNR degradation relative to normal, rather than just "slightly below normal range".  Charles, is there a numeric range associated with these words?

It does seem like a pretty effective test of hearing in noise.  I presume it's doing an adaptive SNR process, since it would usually give me a relatively easy one after each one where I was pretty much guessing.

What I'd like to understand better is exactly how the mechanisms causing threshold elevation also cause degradation of SNR threshold.  I presume that the auditory filter bandwidths are wider, and the compression less, with hearing loss.  But they're also wider at high levels, and high levels don't cause a degraded SNR threshold, do they?  Or maybe they do, in normal hearing, at levels high enough to cause this much bandwidth widening?

I've definitely been feeling a degraded ability to deal with conversation in noisy environments (cafes and such), which I understand is correlated with absolute threshold elevation.  I'm just not clear on why it's so correlated.  Is it understood?  Is there a good paper on this?




On Wed, Oct 30, 2013 at 9:02 AM, Watson, Charles S. <watson@xxxxxxxxxxx> wrote:

I know it is hard to accept that the telephone test works as well as it does, given the experiences we have all had with a range of signal qualities for unselected home telephones.  However the data showed that tests taken with over 100 different home phones used by the veterans in our validation study yielded a similar correlation between the telephone SNR for 50% correct recognition and average pure-tone thresholds to that obtained with the carefully selected telephones used to administer the test in three VA clinics.  We have also tested a sample of different phones to determine the range of distortion and bandwidths, and found them to be acceptable if speech heard over them was not noticeably distorted.

Most importantly, the range of absolute levels delivered by various phones would be quite important if the test measured pure-tone thresholds in the quiet.  The test works because of the insight of Smits and his colleagues that SNR thresholds can be quite reliable under a range of reproductive conditions for which absolute thresholds would be virtually meaningless.

Chuck Watson

-----Original Message-----
From: Tom Brennan [mailto:g_brennantg@xxxxxxxxxxxxxxx]

Sent: Wednesday, October 30, 2013 6:01 AM
To: Watson, Charles S.
Cc: AUDITORY@xxxxxxxxxxxxxxx
Subject: Re: National Hearing Test

Actually, my comments about telephone service are based on having lived in Germany for nearly five years and having a number of friends in Europe.  I do believe their telephone system superior to ours.  This is especially true of their cell phone system but is to a lesser degree of their land lines.

I wonder if some kind of feedback loop could legally be set up to help know what kind of phone system a client doing this test i susing.

Of course, another issue revolves around the fact that most telephones now allow the user to control the volume of the receiver thus adding another confo7unding variable to the mix.


Tom Brennan  KD5VIJ, CCC-A/SLP
web page http://titan.sfasu.edu/~g_brennantg/sonicpage.html


Enrique A. Lopez-Poveda, Ph.D.
Instituto de Neurociencias de Castilla y León
Departamento de Cirugía, Facultad de Medicina
Instituto de Investigación Biomédica de Salamanca
Universidad de Salamanca
Calle Pintor Fernando Gallego 1, 37007 Salamanca, Spain
Phone: (+34)923294500 ext. 1957. Fax: (+34)923294750
Website: http://audiolab.usal.es