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1.4 recommeded additions to wording

From: David MacDonald <befree@magma.ca>
Date: Tue, 2 Nov 2004 22:20:04 -0500
Message-Id: <200411030320.iA33K4ZG019048@mail3.magma.ca>
To: <w3c-wai-gl@w3.org>
Guideline 1.4 Make it easy to distinguish foreground information from
background images or sounds.




Level 3 Success Criteria for Guideline 1.4 


- Audio content does not contain background sounds or the background sounds
are at least 20 decibels lower than the foreground audio content, with the
exception of occasional sound effects. [V] 

Note: A 20 decibel difference in sound level is roughly 4 times quieter (or
louder). Background sound that meets this requirement will be approximately
four times (4x) quieter than the foreground audio content.


Guideline 1.4 (visual-audio-contrast) Issues 


Hi All


I had an action item to provide recommendations on 1.4 based on the open
issues and my research. Until we come up with an alga rhythm much of this
guideline is up in the air. One person recommended an extensive research
study. (Bug#996) Ideally that would be a good idea. I wouldn't mind joining
some people but it would require a team to conduct the size of study he is
suggesting in order to get a statistically meaningful sample size. He also
suggests it would require a statistician. 


Apart from that elephant, I've closed a lot of bugs and I have a couple of
suggestions that might help based on my recent discussions with people in
the audiology field.



Suggested additions are in the <new></new> brackets.


Who Benefits from Guideline 1.4 (Informative) 

Individuals with low vision can easily read characters in the content even
if they don't have the wide field of view or full range of color perception
used by fully sighted persons to separate text from background images. <new>
This will also aid comprehension for individuals with cognitive disabilities
who benefit from easy discernment of text. Visual contrast also helps
individuals with hearing impairments who are aided by clear visual
representation of information </new> 



Add a note to the bottom of the informative section as follows:


<new>Note: Audio Contrast is also known as "signal to noise ratio" by
audiologists, where "signal" refers to the foreground and "noise" refers to
the background.</new>



David MacDonald


Access empowers people...
         .Barriers disable them.


Received on Wednesday, 3 November 2004 03:20:10 UTC

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