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[css3-speech] LC comment: voice-rate percentages

From: Gregory Rosmaita <gregory.rosmaita@gmail.com>
Date: Fri, 30 Sep 2011 23:13:04 -0400
Message-ID: <CAEPrdkBrKeQ=tJUgBkJuj2n9WMgeusvxwMsNfCstQd7ca94rDA@mail.gmail.com>
To: www-style@w3.org, wai-xtech <wai-xtech@w3.org>

in regards voice-rate percentage values, the LC draft of css3-speech

          Only non-negative percentage values are allowed. This
          represents a change relative to the given keyword value (see
          enumeration above), or to the default value for the root
          element, or otherwise to the inherited speaking rate (which may
          itself be a combination of a keyword value and of a percentage,
          in which case percentages are combined multiplicatively). For
          example, 50% means that the speaking rate gets multiplied by
          0.5 (half the value).

COMMENT 1: if the "currently active" voice rate is represented by 100%,
and from that "baseline" scaled up or down (depending upon whether one
wants to increase or deecrease the rate) using positive percentage
values ONLY, then that needs to be explicitly stated in the
css3-speech recommendation.  while the 100% "baseline" concept is far
from novel to those proficient with CSS, it is not an obvious or "self
evident" convention, and therefore should be explicitly stated so as
to eliminate confusion as to how positive percentages greater than
100% can be used to increase voice-rate and how positive percentages
less than 100%, but greater than 0%, are used to decrease voice-rate.


A value less than 100% slows down the voice-rate. Values of greater
than 100% indicate an increase in voice-rate.  The actual rate of
speech relative to the "currently active rate" of 100% is determined
by the capacities of the speech engine being used.

COMMENT 2. as an author and end user, i would be most comfortable using
"voice-rate" to effect small-scale changes in voice rate that are
neither disorienting nor painful for the end user to aurally process:

   body { voice-rate: inherit;
      code { voice-rate: 90%; voice-stress: none;
	     speak-as: literal-punctuation; }
      em { voice-rate: 110%; voice-stress: moderate; }
      strong { voice-rate: 115%; voice-stress: strong; }

authors should also be cautioned against using rate and/or volume alone
or in tandem to indicate a specific type of markup, as control over the
rate and volume of speech and its relative values are EXTREMELY important
user-defined settings, the bounds of which which are based upon the user's
needs, experience, other abilities/disabilities, and the type of content
being converted into speech.

thanks, gregory.

ACCOUNTABILITY, n. The mother of caution.
                 -- Ambrose Bierce, The Devil's Dictionary
     Gregory J. Rosmaita, gregory.rosmaita@gmail.com
      Camera Obscura: http://www.hicom.net/~oedipus/
  Oedipus' Online Complex: http://my.opera.com/oedipus/
Received on Saturday, 1 October 2011 03:13:33 UTC

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