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Re: Reading at variable speeds, NISO/DAISY

From: Jon Gunderson <jongund@ux1.cso.uiuc.edu>
Date: Thu, 30 Nov 2000 10:34:50 -0600
Message-Id: <>
To: Harvey Bingham <hbingham@ACM.org>, w3c-wai-ua@w3.org
I think for checkpoint 4.12 we could use some of this language of digital 
talking books for the minimum speech rate range.  We could say the minimum 
requirement is from 50% of the average speaking rate for a language (i.e. 
180 wpm for English) to 250% of  the average speaking rate for a 
language.  Provide at least 10 geometrically increasing rate settings 
within the range provided.

This is related to issues 401, 402.


At 12:36 AM 11/30/2000 -0500, Harvey Bingham wrote:
>Extract from the joint NISO/DAISY Proposed Standard.
>Digital Talking Books Standards Committee
>Navigation Features List
>NISO Digital Talking Book Standard on Navigation
>     http://www.loc.gov/nls/niso/navigation.htm
>Draft 4, December 29, 1999
>[HB Comments.]
>3. Reading at Variable Speeds
>It should be possible to read the digital talking book at speeds that are 
>faster than or slower than the normal listening rate. This variable speed 
>feature is necessary to enable playback at a speed that is comfortable and 
>efficient for a wide range of readers. Three times the normal "real-time" 
>rate should be possible, and the slowest speed should be around 1/3 the 
>real-time reading rate.
>[HB This doesn't assert what the normal rate is. UAAG 4.12 only places it
>between 120 and 400. My guess is about 180 words per minute. This does not
>address how a user dynamically should be able to adjust that rate.]
>The device should offer the user the option of "Time-Scale Modification" 
>(TSM), that is, the capability to maintain constant pitch while the 
>playback speed is varied. This feature should be optional, however, so 
>that the user can choose to have the pitch change as the playback speed 
>changes. The TSM system should not produce audible chopping, burble, or 
>reverberation and should not skip over significant units of sound at high 
>playback speeds.
>[HB UAAG places no requirement on TSM, maintaining constancy of 
>fundamental voice pitch (but still allowing inflection.) The texts above 
>seem appropriate for notes, properly linked. There is no accommodation to 
>the differences in
>TSM rate with fundamental voice pitch: a female voice already has higher
>frequency, so cannot be speeded up so much without loss of plosives that
>depend on those high frequencies, particularly for someone like me with
>high frequency hearing loss. A male voice takes longer to get such plosives
>started, so sampling them may miss or otherwise distort those plosives,
>even though they should fall within the high-frequency cut-off of the
>hearing loss. I'm uncertain of these assertions, intuited from physics.]
>[HB: Mickey and Gregory, can you clarify please? Do you favor male voice for
>normal narrative, and use female voice for injections of non-running text?
>Do you choose a default rate depending on the gender (as surrogate for the
>fundamental frequency of the voice?]
>Regards/Harvey Bingham

Jon Gunderson, Ph.D., ATP
Coordinator of Assistive Communication and Information Technology
Division of Rehabilitation - Education Services
College of Applied Life Studies
University of Illinois at Urbana/Champaign
1207 S. Oak Street, Champaign, IL  61820

Voice: (217) 244-5870
Fax: (217) 333-0248

E-mail: jongund@uiuc.edu

WWW: http://www.staff.uiuc.edu/~jongund
WWW: http://www.w3.org/wai/ua
Received on Thursday, 30 November 2000 11:34:29 UTC

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