Ever since I updated to Mac OS X 10.5.7 on my main machine, people started complaining that I occasionally sounded like a robot when using Ventrilo. I use a USB headset and thought that they may have modified the USB stack and that Ventrilo would fix the problem. There is a fairly popular thread which has had almost no traction from the developers.
The user wadesworld on the thread found that build 9L22 of 10.5.8 fixes an issue with “USB audio distortion.” I really hope this fixes it.
It seems that Apple has a terrible time with USB. If you recall, back with Tiger I (and many others) had problems with USB and copying files to external hard drives. I went round and round with Apple developers and I don’t think the problem was ever really resolved – it just kinda went cosmic and I moved to Firewire for my Time Machine backup drive.
For now, I look forward to 10.5.8…