Liftering, what is it actually?

I want to know the physical significance of liftering process.

with Ci as ith feature element in the feature vector, the liftering
changes Ci as

 Ci = (1 + (N/2)sin((pi*n)/N))*Ci
 
What is it actually doing to a signal?

Mathematically it is amplifying the signal.

But then, why do we need such an amplification in terms of number of
frames?


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On Monday, August 3, 2015 at 6:43:09 AM UTC-4, proffy wrote:
> I want to know the physical significance of liftering process.
> 
> with Ci as ith feature element in the feature vector, the liftering
> changes Ci as
> 
>  Ci = (1 + (N/2)sin((pi*n)/N))*Ci
>  
> What is it actually doing to a signal?
> 
> Mathematically it is amplifying the signal.
> 
> But then, why do we need such an amplification in terms of number of
> frames?
> 
> 
> ---------------------------------------
> Posted through http://www.DSPRelated.com

Liftering is filtering in the cepstral domain.

Dirk