[Asterisk-Dev] 16 KHz audio ?

[Steve Underwood]

Eric Bart wrote:

>>Actually, it 
>>doesn't take many extra bits to code the higher frequencies. The bulk of 
>>the bits concentrate on the first 4kHz.
>>    
>>
>
>Right. And there's not much compressed rate difference from a 16K to a 24K 
>bandwidth. So why not choose directly 24 KHz ?!
>  
>
Simple. You want a voice oriented codec. Not a music oriented codec. The 
voice oriented ones achieve *much* better results for voice at these low 
bit rates. The voice oriented codecs are not designed for 24kHz 
bandwidth. You *could* design one is, but none of the existing one are.

3.5kHz bandwidth voice == conversationally intelligible
7kHz bandwidth voice == fully intelligible, down to single utterances 
without context
15kHz == really pleasnt warm voice.

Strangely OKish voice needs less bandwidth than OKish music, but good 
voice is actually more demanding of bandwidth than music. The difference 
between 10kHz and 15kHz voice is more obvious than the difference 
between 10kHz and 15kHz music.

Regards,
Steve