Thread Subject: Re: 2.2-D - Volume

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From: Michaelis, Paul R. (Paul)
Date: Thu, Nov 08 2007 4:20 PM

A quick comment on requirement #3:

Audio clipping is not necessarily a bad thing. There are systems that
do peak clipping deliberately as a way to improve intelligibility in
noisy environments. The basic problem is that the high-amplitude events
in human speech (such as voiced vowels) tend to be several dB louder
than the soft events (such as unvoiced fricatives). In noisy
environments, it's possible for high-amplitude speech events to be
audible, while the low-amplitude speech sounds are inaudible due to the
background noise. Making all components of the speech signal louder is
not always a good solution -- e.g., when the audio amplifier does not
have adequate strength. Under these conditions, it can be beneficial to
make the softer speech sounds louder without raising the amplitude of
the louder sounds. Requirement #3 could cause this approach to be
regarded as non-compliant. I'd like to see the requirement reworded so
that modifications of the speech signal that improve intelligibility are
permitted. Thanks,

-- Paul Michaelis

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