Thread Subject: Re: Amplification and Research

Note

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From: Jagbell
Date: Sun, Mar 25 2007 9:25 AM

I am reaching out to the person who performed the ipod test with my
daughter. If he is interested, can he join the group to discuss this
issue?

Best,

Janice


On Mar 25, 2007, at 11:52 AM, Michaelis, Paul R. (Paul) wrote:

> I believe that the issue of intelligibility for hard-of-hearing
> users is
> extremely important. I'm struggling with how to write requirements
> for
> Section 508 that would achieve what we want.
>
> A problem is that many of the techniques that are commonly used to
> assess telecom voice quality are oriented toward differentiating among
> products that, for most people, are fully intelligible. The goal
> is to
> measure perceived quality, rather than intelligibility. This is why
> these tests are described as "subjective" with the results reported
> as a
> "Mean Opinion Score." Although the conduct of such tests is a
> standard
> part of our product development process, I have absolutely no idea
> whether our measures of perceived quality would correlate highly with
> intelligibility among listeners who are hard-of-hearing.
>
> Tests for intelligibility do exist. Examples of procedures that
> rely on
> human assessment include the Diagnostic Rhyme Test and the Modified
> Rhyme Test. Unfortunately, given the wide variation among people who
> are hard-of-hearing, it would be impractical for me to hire a
> statistically valid sample of hard-of-hearing listeners in order to do
> DRT and MRT tests for each of my products. The tests that measure the
> physical properties of the speech -- for example, the amplitude and
> signal-to-noise ratio of the speech at different parts of the acoustic
> spectrum -- work pretty well as a predictor of intelligibility for
> people with normal hearing. Are these tests valid for people who are
> hard-of-hearing?
>
> A bigger problem is that the voice quality in a VoIP system can vary
> tremendously depending on factors that are outside the vendor's
> control,
> and beyond the ability of a typical contract officer to assess. For
> example, an IP network that has excellent voice quality under normal
> conditions may have unacceptable quality when the system is heavily
> loaded with voice traffic -- as might happen during an emergency or
> during times of the day when large numbers of conference calls tend to
> be scheduled. This is because higher levels of traffic can cause
> increased packet loss, packet jitter, and packet latency, along with a
> need to shift from uncompressed G.711 audio encoding to a compression
> technique such as G.729. I have no idea how to write an acceptable
> requirement that addresses this issue.
>
> Despite the complexity of these problems, I'm sure we can do a better
> job for hard-of-hearing users than simply to require support for
> increased amplification. I'm looking forward to hearing people's
> suggestions.
>
> -- Paul Michaelis
>
>
>
>
>
>
>
>
> -----Original Message-----
> From: Jim Tobias [mailto: = EMAIL ADDRESS REMOVED = ]
> Sent: Sunday, March 25, 2007 7:15 AM
> To: 'TEITAC Telecommunications Subcommittee'
> Subject: Re: [teitac-telecom] Amplification and Research
>
> 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 measures 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.
>
>
> ***
> Jim Tobias
> Inclusive Technologies
> +1.732.441.0831 v/tty
> +1.908.907.2387 mobile
> skype jimtobias
>
> -----Original Message-----
> 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
> agreement.
>
> 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
> impacts included.
>
> 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?
>
> David
>
> David Baquis
> Accessibility Specialist
> U.S. Access Board
> 1331 F Street, NW, #1000
> Washington, DC 20004
> 800-USA-ABLE; (202) 272-0013 (voice)
> www.access-board.gov; = EMAIL ADDRESS REMOVED = "Leading the
> way to
> excellence in accessibility"
>
>

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