[Speex-dev] something wrong with narrowband and ultra-wideband?

[Young Free]

I downloaded speex-1.2beta3-win32 binaries, and used the speexenc.exe and speexdec to process the file male.wav download from http://speex.org/samples
I used both the narrowband and ultra-wideband mode:

>speexenc -n --quality 3 male.wav n3.spx
Encoding 8000 Hz audio using narrowband mode (mono)

>speexdec n3.spx n3.wav
Decoding 8000 Hz audio using narrowband mode (mono)
Encoded with Speex speex-1.2beta3

>speexenc -u --quality 3 male.wav u3.spx
Warning: Trying to encode in ultra-wideband (sub-band CELP) at 8000 Hz. I'll do
it but I suggest you try narrowband instead
Encoding 8000 Hz audio using ultra-wideband (sub-band CELP) mode (mono)

>speexdec u3.spx u3.wav
Decoding 8000 Hz audio using ultra-wideband (sub-band CELP) mode (mono)
Encoded with Speex speex-1.2beta3

I believe the ultra-wideband mode would produce more compressed data and better voice quality than 
the narrowband mode. However, I noticed that the facts is contrary: the compressed file u3.spx is smaller than the n3.spx, and the quality of u3.wav are worse than n3.wav. The source file and output files are attached.

Is there something wrong with them ? Could you help me explain this phenomenon?

Regards,
Fred Young
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