[Speex-dev] added background noise problem?

[Scott Roberts]

Using narrow, wideband, and ultra-wideband encoding on a short 16khz wav
gave .spx's of 3,789 ... 2,935  ... and 1,875 bytes. Even after reading the
manual, smaller files for the higher frequency encoding seems
counter-intuitive.  

My mp3 at 32 kbps on the original 22khz wav is 3,866 with a quality
comparable to speex wideband on the converted 16khz wav, so speex is a 24%
improvement in size. The mp3 had a little more (but acceptable) hiss, but
it had better sharpness in the higher frequencies (hence the hiss).
Overall i rank the quality even.  I tried LAME mpeg-2 layer 3 on the
converted 16khz wav, but i still had to go up to 32 kbps (same file size)
to get the same quality as speex wideband.  So all in all, i estimate speex
to have a 25% better quality/size ratio than mp3 on high quality speech.

Maybe a speex expert could do better settings, but maybe so too could mp3.
But maybe implementation by a novice user is part of a valid comparison
even if my methodology isn't perfect.