How does Vorbis fare for speech compression?
It works well, but is generally not the optimal solution. Vorbis is designed for the compression of music and general purpose audio. Special purpose codecs can achieve much greater compression of speech than Vorbis. Vorbis also tends to have a latency that is too high for telephony, a common use of speech codecs. Read the Speech Coding and Compression FAQ for more details. Those looking for an open-source, patent-free speech codec should take a look at Speex.
