Sound Conversion
Presented by:         
Chilin Shih , University of Illinois, Urbana–Champaign  
Project / Software Title :      
Sound Conversion – – SoX  
Project / Software URL:
Access / Availability:       This is an open source software.

SoX– –Sound eXchange– – was originally written by Lance Norskog . It is an open source software for UNIX and DOS, which is now supported by many contributors. As the author puts it, it is the Swiss Army Knife of sound tools. You can do many things such as converting sound format, changing sampling rate, and adding sound effects.

For example,
sox emeld.aiff emeld.wav
converts a sound file emeld.aiff from the .aiff format to the .wav format.
sox emeld.wav -r 8000 emeld8k.wav
gives us an output file emeld8k.wav with the sampling rate 8000 Hz.

Note that when we down-sample a speech file, we will lose speech quality which we cannot recover. So keep the original as backup.

In the ideal world we won’ t need sound conversion. People all agree and use the best sound format, and there is only one best format.

In the real world, we don’ t know what is best, we don’ t agree with each other, and we all use different sound formats. Sometimes there are good reasons. "Best" is a context–sensitive concept. High sampling rate is the best choice for storing speech files for archival purposes when you have ample storage space. Low sampling rate may be the best choice if you need smaller file size for file transmission.

As a result, my speech files is not compatible with your computer, and my current play program won’ t play last year’ s speech files. This is when you can use a sound conversion program.

We know that operating systems change faster than we can adapt, and companies surface and burst like bubbles. So if you can, use open source programs, and stay away from proprietary file formats to increase the chance that you can access your speech files a few years down the line.


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