Why JavaGran?
You've probably had the experience of hearing a tape recorder slow down as it's playing; perhaps when the batteries died (or when a tape was being mulched!). You may have noticed that as the sound slowed the pitch also dropped. The inverse is true with a tape speeding up: The sound gets faster and the pitch gets higher. You can hear this effect if you play the soundfile (mp3) below:
From this you can see that there is a direct connection between the speed (or duration) of a sound and its pitch. You may have also realised that this works more or less the same with digital soundfiles (like the mp3 file above) as it does with analog tape recorders. Composers interested in making music with computers found this to be a problem. They wanted to be able to vary the pitch and duration of sounds independently. They came up with a number of ways to do this. One of them is called granulation of soundfiles.
Granulation or 'granular time-stretching' allows you to vary either the pitch or duration of a sound without changing the other aspect. So one could take a single word like 'Beauty' and make it last three times as long without causing the pitch to go down.
An interesting side effect of processes such as granulation is that they can add new elements to the sound that weren't derived from something in the original. These are referred to as 'artifacts', since they are something left over which shows that the sound has been processed. Granulation has its own unique set of artifacts, and other types of processing have their own. Since artifacts don't correspond to anything in the original, they might be considered unnatural, but computer musicians don't necessarily worry about this (what's natural about a word stretched to three times its length anyway?). In fact some composers actually seek to amplify and bring out artifacts, appreciating them for their own sake. This is part of a larger philosophy of learning to appreciate sounds for their sonic qualities, as well as for their meanings. One of the wonderful things about stretching a sound is in fact the hidden details this can bring out.
> Click here to learn how granulation works...
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