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3D Audio -improving HRTF filtering

Hi all,

I am working on 3D-Audio based on HRTF filtering.

My starting point is KEMAR data from MIT media labs, done by bill
gardner and Keith Martin.

I have implemented a basic by referering to the demo SGI code provided
in MIT site.

My first implementation is just time domain convolution , which works
wothout any noise.

But for efficient implementation I am trying to move to frame based
processing, as in the SGI code provided in the MIT website.

the steps involved in my new implemantation are ...

1) take 1024 number of samples.
2) Window those 1024 samples. (for this I am now using kaiser window of beta=16)
3) Take 1024 point FFT the input
4) Zero pad the 128 point HRTF filter to make it 1024 point.
5) Take 1024 FFT of HRTF Left ans Right data.
6) Multiply the spectrum in frequency domain.
7) Take 1024 point IFFT of the resultant spectrum.
8) Do a 75 % overlap and add.

But a minor amout of noise is present in the o/p ....

As a general instruction ... how can I improve the SNR of the o/p ?????

I have tried , diferent type of windows, and overlap of 50 % also ..

Any lights in to this ... ????