how to copy just part of a file?

[BSD baby]

Is there an easy built-in way to copy only part of a file?

I want to take a WAV audio file and copy from #__ bytes to
#___ bytes into a new file.

(I'm making 30-second clips of files.)

Though I found a scripting way to do it with PHP, I'm wondering
if there's a more direct way to do it with basic GNU/BSD commands.

Anyone?