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Comment of 4.12 speech playback rate

From: Phill Jenkins/Austin/IBM <pjenkins@us.ibm.com>
Date: Mon, 13 Nov 2000 23:19:48 -0500
To: w3c-wai-ua@w3.org
Cc: "Richard Schwerdtfeger/Austin/IBM" <schwer@us.ibm.com>, "Catherine Laws/Austin/IBM" <claws@us.ibm.com>
Message-ID: <OF2E65D03E.CA6FC2AA-ON86256997.001180CF@raleigh.ibm.com>
Checkpoint 4.12 Allow the user to configure and control synthesized speech
playback rate according to the full range offered by the speech
synthesizer. The lower bound for this range must be at most 120 words per
minute. The upper bound for this range must be at least 400 words per
minute. The user must be able to increase or decrease the playback rate in
increments of 5% of the current playback rate. P1.

Splitting or reducing the checkpoint wording and editorial changes should
provide further clarification and implementability:

1. Suggest changing the phrase
"lower bound must be at most 120 words per minute"
"lower bound must be 120 or less words per minute"

2.  The term "words per minute" may not make sense with all synthesizers,
especially Japanese and Chinese synthesizer which do not use the concept of
"words".  I will send a note to the list when I receive a reply from a
Japanese speech synthesizer as to their definition of "speech rate".

3. The middle phrase: "The lower bound ... and the upper bound ..." could
be moved entirely to the techniques document.  Checkpoint 4.10 does not
specify the range of the volume, other than zero.  Why does 4.12 need to
specify the "speech rate" range, other than the "full range offered by the
speech synthesizer"?

4.  The last phrase in the checkpoint: "The user must be able to increase
or decrease the playback rate in increments of 5 percent of the current
playback rate" could be moved entirely to the techniques. The first phrase
alone could be sufficient for the checkpoint wording: "Allow the user to
configure and control the full range of the synthesized speech playback

5.  The desired objective or goal of the last phrase needs to be explained
and then used as the checkpoint wording, if it remains in the checkpoint.
For example, if the goal is to provide for an efficient or "fast" way for
the user to change the playback rate, a technique that uses a combination
of a linear 10 increment scale [using the up arrow key] with larger jumps
of 50 or 100 [using the page up key] would provide a faster way of
increasing the playback rate.  A technique to enter the exact rate desired
could be another excellent choice.  The intent of the checkpoint should be
to allow UAs to be compliant but still compete on implementation.  If the
goal of the checkpoint is to provide finer control in changing the playback
rate - then that rational for "fine control" needs to be explained.  The
goals of "finer control" and "efficient change", at times, are opposing
goals.  The current wording is too prescriptive and edicts the
implementation approach without explaining the goal.

Phill Jenkins,
IBM Research Division - Accessibility Center
Received on Monday, 13 November 2000 23:23:59 UTC

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