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Difference between LPC & LPC vocoder

Started by September 10, 2007
I'm doing a speech recognition project. Can LPC vocoder be use for
speech rocognition?
Can anyone help me with the differences between LPC and LPC vocoder?
I'm looking at the code which i found in the net and it seems that LPC
method were used in LPC vocoder and it is dealing with pitch. I'm not
so sure about cross corelation as i've read somewehre, they say use
auto correlation and covariance but inside LPC vocoder, they used
cross correlation. Clarify me pls..
Thanks!

>I'm doing a speech recognition project. Can LPC vocoder be use for >speech rocognition? >Can anyone help me with the differences between LPC and LPC vocoder? >I'm looking at the code which i found in the net and it seems that LPC >method were used in LPC vocoder and it is dealing with pitch. I'm not >so sure about cross corelation as i've read somewehre, they say use >auto correlation and covariance but inside LPC vocoder, they used >cross correlation. Clarify me pls.. >Thanks! > >
auto correlation / covariance in LPC vocoder: for levinson recursion. inside LPC vocoder, they used cross correlation : for pitch determination pitch determination is an important part for synthesis , ie reconstruction of speech. Levinson recursion is important part of analysis. In fact if you pass the error from levinson analysis thru the levinson filter(LPC filter) you get the original siignal back. But because the error is long term stationary ( bumpy at pitch periods) people thought about ways to reduce the redundancy and hence pitch analysis. as you can guess in synthesis, pitch information is used to generate the excitation signal , which should look like the levinson error signal.
On Sep 10, 5:48 pm, "pal.debabrata123" <pal.debabrata...@gmail.com>
wrote:
> >I'm doing a speech recognition project. Can LPC vocoder be use for > >speech rocognition? > >Can anyone help me with the differences between LPC and LPC vocoder? > >I'm looking at the code which i found in the net and it seems that LPC > >method were used in LPC vocoder and it is dealing with pitch. I'm not > >so sure about cross corelation as i've read somewehre, they say use > >auto correlation and covariance but inside LPC vocoder, they used > >cross correlation. Clarify me pls.. > >Thanks! > > auto correlation / covariance in LPC vocoder: for levinson recursion. > inside LPC vocoder, they used cross correlation : for pitch determination > > pitch determination is an important part for synthesis , ie reconstruction > of speech. > Levinson recursion is important part of analysis. > In fact if you pass the error from levinson analysis thru the levinson > filter(LPC filter) you get the original siignal back. > But because the error is long term stationary ( bumpy at pitch periods) > people thought about ways to reduce the redundancy and hence pitch > analysis. > as you can guess in synthesis, pitch information is used to generate the > excitation signal , which should look like the levinson error signal.
Hi Thanks for your explanation. Would you mind to brief me the procedure for Lpc vocoder? I'm actually very new to this. Correct me if i'm wrong. I follow what i understand about the code i found and the info i read. Pre-empahsis-->Windowing--->Cross correlation using Levinson Method Gain calculation--->pitch & voicing The output for both of this method is the analysis we want for speech recognition, speech to text Actually, gain calculation is for what purpose? If i'm doing speech to text recognition, it's sufficient for me to use only the encoder part.am i right? If you dun mind to help me see the code, I'm willing to send. Thanks alot.