For encoding in OGG, it's best to use 96-196kbps. Personally, I recommend 128kbps for all audio, though I'll accept 196 for high quality music, though there is hardly any difference between 128 and 196 kbps, and certainly not enough to justify larger filesizes when you have so many other sounds playing at the same time too. For voices, you can use 48kbps fine, though 96kbps is more apt for sounds.
Over 196kbps should never be used.