I just tried it with speex's wideband setting, and I was able to recover the transmitted message. I had to modify the wav file generator to output in 16-bit PCM

I just tried it with speex's wideband setting, and I was able to recover the transmitted message. I had to modify the wav file generator to output in 16-bit PCM instead of float, which speexenc doesn't support. The narrowband profile also works, but I needed to create a new Quiet profile with a center frequency of 2200Hz.