Flash Audio

Accessible Flash Streaming Audio

by Daryl Croke

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Accessible Flash Streaming Audio

The following article will focus on methods and issues involved with delivering streaming audio content for the visually impaired. Although not intended as a tutorial as such, I will describe some techniques for building an audio console in Flash MX that streams mp3 files. As audio developers we are in a unique position to provide exciting applications for visually impaired Internet users.

At the moment most visually impaired users access the web with the use of screen readers and audio browsers. These applications convert text on a HTML page to a computer-generated voice. Users navigate through the page and access links by using keystrokes. Typically the voices are monotone and unappealing. Users can choose which voice to read the page and select the speech rate (words per minute).

Streaming audio offers a number of potential advantages for the visually impaired. One of the most obvious is the ability to listen to music over the net. For example, the American Council of the Blind (ACB) has an excellent radio station which uses mp3 streaming, http://www.acbradio.org/.

Another advantage that streaming audio content has over text to voice technologies is more effective narration. Screen readers are rather dumb and have a hard time coping with inconsistencies of the spoken language. For example words that are spelt the same but pronounced differently. Another issue is when to read out a number as an amount or by each digit. Ask yourself would you rather listen to a human read out a web page or a computer generated voice?

Note: To improve the aural rendering by screen readers of text content the W3C have recently released a new standard called Speech Synthesizer Mark-up Language.

There are many technical issues involved in delivering streaming audio content to a web user accessing the net through a screen reader. Not least being how to control the playback without the use of a mouse. Will the user be able to start, stop and most importantly exit the application/player using only keystrokes? Another complication is that screen readers are available on PC, Mac and Linux platforms. Some screen reader/platform combinations don’t recognise Flash or cope with JavaScript.

Commercial benefits for developing streaming audio content for the visually impaired are hard to determine. There are a number of sites at the moment that offer narration of popular books over the net. One thing is sure; the section of the population with significant visual problems is growing. According to the Vision Australia Foundation, approximately 380,000 people in Australia suffer legal blindness or low vision. The number is expected to double in the next 20 years, due to the ageing population. Add to those figures the millions of Australians who are illiterate or have English as a second language and the need for some aid to speak the contents of web sites become evident.

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