Speex is an Open Source/Free Software patent-free audio compression
format designed for speech. The Speex Project aims to lower the barrier
of entry for voice applications by providing a free alternative to 
expensive proprietary speech codecs. Moreover, Speex is well-adapted 
to Internet applications and provides useful features that are not 
present in most other codecs. Finally, Speex is part of the GNU  
Project and is available under the revised BSD license.