🚀 go-pugleaf

Dario Antonio Palhares Carvalho de Freitas Diogo <falphaxt@cc.fc.ul.pt> wrote:
>
> 
> What is (phase?) vocoder? I gather it's an advanced audio DSP algorithm, 
> but what's it about axactly?
> 
> I've already serched the internet for information but couldn't find 
> anything specific.
> 
> If you can help me, please e-mail your answer to the address below.
> 
> 
> Thanx in advance...
> 
> > -----------------------------------------------------------------------------
>                   falphaxt@cc.fc.ul.pt ----- Dario Diogo
> -----------------------------------------------------------------------------
> 
> 
> 
VOCODERS have been used for secure transmission of voice for almost
50 years.  The original VOCODERS would analyse voice spectrum and 
the transmit the amplitude of each frequency band, and the amplitude
and frequency (pitch) of the voice or the amplitude of noise for
unvoiced sounds.

Modern VOCODERS use 10th order Linear Predictive Coding to analyse
voice.  Sampled voice (8 KHz sample rate) is analysed 50 times a
second to determine the shape of the vocal tract.  The ten "areas",
and the amplitude and frequency (pitch) of the voice or the amplitude
of noise for unvoiced sounds is sent every fiftieth of a second.

See Federal Standard 1015:  Analog to Digital converson of Voice by
2400 bit/second Linear Predictive Coding.  Published by General Services
Admisintration, Office of Information Resources Management.
(Date on this standard is 28 Nov 1984.)

  --  Russ