GNU and FSF tell WBUR.org Boston: PlayOgg!

(I am the author of Speex)
Speex is indeed designed for VoIP in mind, although it has other applications. When it comes
to choosing Speex vs Vorbis for applications like speech-only radio, here's the rule of thumb
I always suggest. If your target bit-rate is above ~32 kbps, use Vorbis, if below, use Speex.
Of course, that's a rule of thumb and the exact application can change things. Speex does
worst on music than Vorbis, but it does much better than Vorbis in case of packet loss. If
used properly (at 16 kHz and not 44.1 kHz as some idiots try to use it), Speex will give you a
quality that's somewhere between AM and FM radio.