```I think what you are looking for is how to approximate a given impulse
response (FIR system) through a system with rational transfer
function. You can start searching using "model order reduction" and
"system identification".

Zot wrote:
> O.K. thanks.
> If I convolve a sample of say a drum with a long fading out white noise
> impulse, I get a really nice gradual fading drum sound, that's all and mixed
> up and blurred out through time, which is what I termed diffusion.
> If I'm doing a 1024 point FFT to convolve through this white noise, do I
> really need the large white noise impulse, because large convolutions take
> longer to calc? Is there a way to populate the 1024 FFT every block using
> some kind of residue of the old FFT and  new random numbers?  The more I
> (try to) explain this, the more it sounds unlikely, as each sample has to be
> multiplied by the whole of the existing noise sample.. hmmm... head hurting,
> must stop!
>
> Cheers,
>
> Dave
>
> "Andor" <andor.bari...@gmail.com> wrote in message
>
>
>
>
>
>
> > Zot wrote:
> >> I guess I'm either barking up the wrong tree or exactly the right one!
>
> > I still don't know exactly what your question is. You want to use
> > white noise as reverb, and somehow compress the white noise to reduce
> > the "table size" (what table?)? You know that you can't compress white
> > noise (by definition). Can you elaborate on your goal / problem a bit?- Zitierten Text ausblenden -
>
> - Zitierten Text anzeigen -

```
```O.K. thanks.
If I convolve a sample of say a drum with a long fading out white noise
impulse, I get a really nice gradual fading drum sound, that's all and mixed
up and blurred out through time, which is what I termed diffusion.
If I'm doing a 1024 point FFT to convolve through this white noise, do I
really need the large white noise impulse, because large convolutions take
longer to calc? Is there a way to populate the 1024 FFT every block using
some kind of residue of the old FFT and  new random numbers?  The more I
(try to) explain this, the more it sounds unlikely, as each sample has to be
multiplied by the whole of the existing noise sample.. hmmm... head hurting,
must stop!

Cheers,

Dave

"Andor" <andor.bariska@gmail.com> wrote in message
>
>
> Zot wrote:
>> I guess I'm either barking up the wrong tree or exactly the right one!
>
> I still don't know exactly what your question is. You want to use
> white noise as reverb, and somehow compress the white noise to reduce
> the "table size" (what table?)? You know that you can't compress white
> noise (by definition). Can you elaborate on your goal / problem a bit?
>

```
```
Zot wrote:
> I guess I'm either barking up the wrong tree or exactly the right one!

I still don't know exactly what your question is. You want to use
white noise as reverb, and somehow compress the white noise to reduce
the "table size" (what table?)? You know that you can't compress white
noise (by definition). Can you elaborate on your goal / problem a bit?

```
```I guess I'm either barking up the wrong tree or exactly the right one!

Nizza, wenn jemand mir einen Tip gab.

"Andor" <andor.bariska@gmail.com> wrote in message
> On 14 Mrz., 23:10, Jerry Avins <j...@ieee.org> wrote:
>> Andor wrote:
>>
>>    ...
>>
>> >> - Zitierten Text anzeigen -
>>
>> Zitierten Text anzeigen?
>>
>
> Aber klar doch!
>
> Gruss,
> Andor
>

```
```On 14 Mrz., 23:10, Jerry Avins <j...@ieee.org> wrote:
> Andor wrote:
>
>    ...
>
> >> - Zitierten Text anzeigen -
>
> Zitierten Text anzeigen?
>

Aber klar doch!

Gruss,
Andor

```
```Andor wrote:

...

>> - Zitierten Text anzeigen -

Zitierten Text anzeigen?

Jerry
--
Engineering is the art of making what you want from things you can get.
&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;
```
```In diffusion, I meant something similar to the long drawn out tail of a
reverb unit. Normally done with a bank of different length delay lines in
parallel to blur the sound. The trouble with this method is that you have to
apply a lot of delays and add modulation and countless listening tests and
tweaking to make it acceptable and non-metallic - Which is fine, but I
noticed that convolving a white noise signal with it did a fine job also. So
I was wondering if it was a valid solution, and also if the impulse could be
long tails.
I hope that makes sense!

Dave

"Andor" <andor.bariska@gmail.com> wrote in message
> What is a "diffusion sound" ?
>
> On 13 Mrz., 05:19, "Zot" <b...@yahoo.com> wrote:
>> Oh, nevermind. Be all that ends all.
>>
>> "Zot" <b...@yahoo.com> wrote in message
>>
>> news:J2cJh.132269\$HO5.95382@fe1.news.blueyonder.co.uk...
>>
>>
>>
>> > Hi folks, I was experimenting with convolution, using the the
>> > ideas with FFT. I was using an impulse of  fading white noise to test
>> > the
>> > algorithm for smoothness, and I noticed to made an almost perfect
>> > diffusion sound.
>>
>> > My question; is it possible to feed the FFT with white noise and a
>> > mixture
>> > of the previous noise or something to create a nice diffusion fall-off
>> > without using a huge noise table? Basically having a nice long
>> > diffusion
>> > tail without the massive impulse. I have tried diminishing the noise
>> > then
>> > adding a new random set on top with each frame, but I only got very
>> > repetitive buzzing, could this or something similar actually work?
>>
>> > Thanks,
>> > Dave Hoskins- Zitierten Text ausblenden -
>>
>> - Zitierten Text anzeigen -
>
>

```
```What is a "diffusion sound" ?

On 13 Mrz., 05:19, "Zot" <b...@yahoo.com> wrote:
> Oh, nevermind. Be all that ends all.   : ) If you know anyone that says the
> words "Paradigm shift,"  then your with the wrong company.  : ) ...... .....
> .... ... .. .
>
> "Zot" <b...@yahoo.com> wrote in message
>
> news:J2cJh.132269\$HO5.95382@fe1.news.blueyonder.co.uk...
>
>
>
> > Hi folks, I was experimenting with convolution, using the the overlap-add
> > ideas with FFT. I was using an impulse of  fading white noise to test the
> > algorithm for smoothness, and I noticed to made an almost perfect
> > diffusion sound.
>
> > My question; is it possible to feed the FFT with white noise and a mixture
> > of the previous noise or something to create a nice diffusion fall-off
> > without using a huge noise table? Basically having a nice long diffusion
> > tail without the massive impulse. I have tried diminishing the noise then
> > adding a new random set on top with each frame, but I only got very
> > repetitive buzzing, could this or something similar actually work?
>
> > Thanks,
> > Dave Hoskins- Zitierten Text ausblenden -
>
> - Zitierten Text anzeigen -

```
```Oh, nevermind. Be all that ends all.   : ) If you know anyone that says the
words "Paradigm shift,"  then your with the wrong company.  : ) ...... .....
.... ... .. .

"Zot" <bob@yahoo.com> wrote in message
news:J2cJh.132269\$HO5.95382@fe1.news.blueyonder.co.uk...
> Hi folks, I was experimenting with convolution, using the the overlap-add
> ideas with FFT. I was using an impulse of  fading white noise to test the
> algorithm for smoothness, and I noticed to made an almost perfect
> diffusion sound.
>
> My question; is it possible to feed the FFT with white noise and a mixture
> of the previous noise or something to create a nice diffusion fall-off
> without using a huge noise table? Basically having a nice long diffusion
> tail without the massive impulse. I have tried diminishing the noise then
> adding a new random set on top with each frame, but I only got very
> repetitive buzzing, could this or something similar actually work?
>
> Thanks,
> Dave Hoskins
>
>
>

```
```Hi folks, I was experimenting with convolution, using the the overlap-add
ideas with FFT. I was using an impulse of  fading white noise to test the
algorithm for smoothness, and I noticed to made an almost perfect diffusion
sound.

My question; is it possible to feed the FFT with white noise and a mixture
of the previous noise or something to create a nice diffusion fall-off
without using a huge noise table? Basically having a nice long diffusion
tail without the massive impulse. I have tried diminishing the noise then
adding a new random set on top with each frame, but I only got very
repetitive buzzing, could this or something similar actually work?

Thanks,
Dave Hoskins

```