we may want/need a way for the server to determine what audio formats a client 
supports for the purposes of returning captured audio. Right now we don't even 
have a way for the client to tell the server what format it wants audio returned 
in, so we at least have to remedy that omission.

See http://www.ietf.org/mail-archive/web/speechsc/current/msg01387.html for 
discussion