Thread Subject: Re: Amplification and Research
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From: Jim Tobias
Date: Sun, Mar 25 2007 6:20 AM
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David, you are quite right to differentiate between amplification and
clarity, of course. A louder bad signal is not a better signal. Except in
rock music, of course.
Clarity itself is made up of several different characteristics, as Paul has
already responded. I readily admit to not being an expert in this area.
But I do know that there is a set of industry measures (or at least testing
protocols and metrics) for intelligibility that are commonly applied to
telephones. In fact, there's a whole family of them, P.800 from ITU, and
another one from ITU, G.107. Most (all?) of these use subjective testing: a
bunch of people listen to the audio and rate it on a scale of
intelligibility. (Who is in that bunch, of course, is an interesting
question -- you have to wonder if they automatically rule out anyone with
any hearing loss!) The answer is a number. For the most common metric, MOS
(great to have an acronym, but all it stands for is "mean opinion score"), a
rating above 4.0 out of 5.0 is considered good.
TEITAC or the Access Board could decide to research this issue to find out:
1. if any other worldwide accessibility regulations use one or more of these
2. if any US regs for any purpose use one or more of these measures
3. if procurement ever includes any such requirements
4. which, if any, of the metrics are commonly used by vendors
and perhaps other points about the utility and feasibility of adopting a
metric. One interesting question would be to map the metric onto the world
of hearing loss. For example, how many people with what kind and degree of
hearing loss can detect a difference between a 3.5 and a 4.5 MOS.
From: Baquis David [mailto: = EMAIL ADDRESS REMOVED = ]
Sent: Monday, March 12, 2007 4:03 PM
To: = EMAIL ADDRESS REMOVED =
Subject: [teitac-telecom] Amplification and Research
I have skimmed an archived thread of discussion about amplification as well
as listened to part of today's call. Here are my thoughts as you prepare to
present your work-to-date to the TEITAC:
Remember that you can recommend that the Access Board research an issue.
We would likely do that by funding a contractor. Your recommendations need
not be limited to comments about the Standards/Guidelines.
Would you like research on what is sufficient for hearing access over the
telephone? I know, of course, that the answer to this is complex since there
are different types of hearing loss, telephones, situations, etc. And yet,
you are recommending design standards to help with such access.
For a second, let's set aside the legal issues as well as the burden and
begin with an understanding of what people who are hard of hearing really
need for accessibility, if we can. In this paragraph, I am not addressing
what problems we might encounter if we try to accomplish this. I am simply
asking what is truly helpful.
* When is 20 dB, 25dB, up to 40dB beneficial? Are these demands
based solely on anectodal reports? If there is a science to this, shouldn't
we discover it? If it is already known, could it be referenced as a basis
for rulemaking? If we do not know this with research-based certainty,
wouldn't you like to recommend that it be investigated?
* How does clarity interrelate with amplification? If clarity is
improved, does that partially reduce the need for high gain? Does the
subcom need technical information on what specific elements make up clarity?
* Is a separate standard for clarity needed?
* Any other questions regarding maximizing residual hearing to add
to this list?
Looking back to Brenda's email from November 6, 2006, I see that HLAA
commissioned lab research to address distortion. Would it be helpful to the
TEITAC to know of other research, such as this, which could help inform
rulemaking? Brenda, do you want to post that research on the wiki (or ask
Tim to do it). If the TEITAC feels that distortion caused by amplification
is a non-issue then perhaps that should be stated clearly as a point of
Since we are looking at both 255 and 508, consider the impact not only on
the government customer (508) but on the individual consumer (255).
Of course there is the impact on manufacturers too, so you may want to lay
this out in an easy to follow chart - with both positive and negative
With regard to Paul's comment on battery drain to provide amplification at
higher levels, you may want to consider commenting on wireless and wireline
separately if that makes a difference in respective impact. I am imagining
not only economic impact, but consumer satisfaction with a phone that may
not work as well.
However, I am also imagining that the past does not equal the future.
What feels impossible now may become possible in the future with
improvements in batteries, processing, etc.
Oh and don't forget VoIP and network-based amplification when you consider
possibilities and impacts. Do you imagine old technology or new technology
when discussing this? Must the power for the volume always be contained
inside the phone set? How far away are we from the day when our preferred
hearing interface can be profiled -- and we can virtually bring that profile
with us from phone to phone (or multiple profiles depending on changes in
environment, congested hearing, etc)? And what would be the hardware
requirements to support a network-based solution?
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