Since people wondered here is a quick demonstration of speex.
Here is an MP3 recorded at 96kbsec it’s 768KB in size, as a raw wav file:
Here it is in speex, at 54kb in size
And again in speex at 29kb in size
So while the ‘narrow’ file sounds ‘bad’ you can understand them, the ‘wide’ version sounds pretty good, and being a fraction of the size is a ‘good thing’ IMHO.