Re: [music-dsp] idealized flat impact like sound

[gm]

Am 02.08.2016 um 10:55 schrieb Uli Brueggemann:
Maybe I miss the real question of the topic but I have played around 
with creating a FIR filter:

1. generate white noise of a desired length
2. window it with an exponentially decaying envelope
3. apply some gain, e.g. 0.5
4. add a Dirac pulse at the first sample
The result is sprectrally not flat but
5. compute the excessphase of the sum = allpass = spectrally flat and 
use it


I don't get it to work, some questions:

when I convolve the original with the excess phase signal, shouldn't I 
get a minimum phase signal again?

(I dont)

what is the expected wave shape for the excess phase signal then?
(I get an arbitry mixed phase signal, not a one sided decaying signal
- but that is also what I would have expected though -?)

or do I need the unwrapped phase to calculate the excess phase?



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Re: [music-dsp] idealized flat impact like sound

[Uli Brueggemann]

Maybe I miss the real question of the topic but I have played around with
creating a FIR filter:
1. generate white noise of a desired length
2. window it with an exponentially decaying envelope
3. apply some gain, e.g. 0.5
4. add a Dirac pulse at the first sample
The result is sprectrally not flat but
5. compute the excessphase of the sum = allpass = spectrally flat and use it

- Uli


2016-08-02 2:31 GMT+02:00 gm :

>
>
> Am 01.08.2016 um 22:55 schrieb Evan Balster:
>
>> The most essentially flat signal is a delta function or impulse, which is
>> also phase-aligned.  Apply any all-pass filter or series thereof to the
>> impulse, and the fourier transform over infinite time will remain flat.  I
>> recommend investigating Schroeder filters.
>>
>
> I already played with them as well as FDNs.
> Though Shroeder allpass filters in series (or reverbs in general) are not
> strictly flat it's better than random.
>
> And it's a trade off to have an impact like onset.
> You get that "like gaussian smear" smear, unless you set your diffusion
> coefficient high
> which also makes the responses longer. And the onset ist a little bit
> unnatural.
> (I know you can "nest" them and change that a little bit)
>
> Either way this way it comes down to reverb design... which quite a trap
> to waste time with...
> it's never finished in a way, at least for me
>
> And related to reverbs, the question:
> - how do I create a spectrally flat short decaying noise-like and
> impact-like sequence
> becomes interesting again, I think.
>
> But maybe there is nothing that's better than Shroeder allpass?
> I started to use random sequences for early reflections but found that
> these colors the sound too much, so I basically came to the same question.
> Though for reverb a more sparse noise would be better...
>
> And for allpass delays the question remains
> - how to design optimal length ratios?
> That's why I made the slightly nonsense remark about RNGs and reverbs the
> other day.
>
> So far I just use my ears, assumptions and numerology.
>
>
>
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Re: [music-dsp] idealized flat impact like sound

[gm]

Am 01.08.2016 um 22:55 schrieb Evan Balster:
The most essentially flat signal is a delta function or impulse, which 
is also phase-aligned.  Apply any all-pass filter or series thereof to 
the impulse, and the fourier transform over infinite time will remain 
flat.  I recommend investigating Schroeder filters.


I already played with them as well as FDNs.
Though Shroeder allpass filters in series (or reverbs in general) are 
not strictly flat it's better than random.


And it's a trade off to have an impact like onset.
You get that "like gaussian smear" smear, unless you set your diffusion 
coefficient high
which also makes the responses longer. And the onset ist a little bit 
unnatural.

(I know you can "nest" them and change that a little bit)

Either way this way it comes down to reverb design... which quite a trap 
to waste time with...

it's never finished in a way, at least for me

And related to reverbs, the question:
- how do I create a spectrally flat short decaying noise-like and 
impact-like sequence

becomes interesting again, I think.

But maybe there is nothing that's better than Shroeder allpass?
I started to use random sequences for early reflections but found that 
these colors the sound too much, so I basically came to the same 
question. Though for reverb a more sparse noise would be better...


And for allpass delays the question remains
- how to design optimal length ratios?
That's why I made the slightly nonsense remark about RNGs and reverbs 
the other day.


So far I just use my ears, assumptions and numerology.


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Re: [music-dsp] idealized flat impact like sound

[Evan Balster]

The most essentially flat signal is a delta function or impulse, which is
also phase-aligned.  Apply any all-pass filter or series thereof to the
impulse, and the fourier transform over infinite time will remain flat.  I
recommend investigating Schroeder filters.

– Evan Balster
creator of imitone 

On Sat, Jul 30, 2016 at 5:39 PM, gm  wrote:

> I think it's interesting for instance for early echoes in a reverb.
> For longer sequences it seems to become very self-similar?
>
> I only looked into the thing under "Additive recurrence", the rest is
> totally above my head, and played around with this a little bit, since it's
> basically a random number generator with "bad parameters" there.
> I tried similar things before with the golden ratio, bascially even the
> same thing I just realize.
> Like panning in a seemingly random fashion with golden ratio mod 1.
>
> With little sucess in reverbs, though, for instance most of the time it's
> not a great
> idea to just tune delay lengths to golden ratios...
>
> But maybe it's useful for setting delay lengths in a different way?
>
> Just seeing the similarity between a classical reverb algorithm and random
> number generators
> with the feedback loop acting as mod operator.. didn't see it like that
> before
>
> Did anybody build a reverb based on a random generator algorithm?
> Or are reverbs just that and it just never occured to me?
>
> What I also wonder is the difference between a sequence like that (or any
> random sequence)
> and a sequence thats synthesized with FFT to be flat but with random
> phases.
> I wonder what's better in terms of what and why, when it comes to reverb
> and/or convolution,
>
>
>
> Am 30.07.2016 um 19:57 schrieb Patric Schmitz:
>
>> Hi,
>>
>> On 07/28/2016 08:43 PM, gm wrote:
>>
>>> My problem was that a short segment of random isn't spectrally
>>> straigh-line flat.
>>>
>> On 07/30/2016 07:22 PM, gm wrote:
>>
>>> Just a short sequence of random numbers really exhibits large
>>> formant like fluctuations .
>>>
>> I tried following this discussion even though, admittedly, most
>> of it is way over my head. Still, I wonder if the problem of
>> short random sample sets being too non-uniformly distributed
>> could be alleviated somehow, by not using white noise for the
>> samples, but what they call a low-discrepancy quasi- or subrandom
>> sequence of numbers.
>>
>>> https://en.wikipedia.org/wiki/Low-discrepancy_sequence
>>>
>> I heard about them in a different context, and it seems their
>> main property is that they converge against the equally
>> distributed limit distribution much quicker than true random
>> samples taken from that distribution. Maybe they could be useful
>> here to get a spectrally more flat distribution with a fewer
>> number of samples?
>>
>> As said, I'm by far no expert in the field and most of what has
>> been said is above my level of understanding, so please feel free
>> to discard this as utter nonsense!
>>
>> Best regards,
>> Patric Schmitz
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Re: [music-dsp] idealized flat impact like sound

[gm]

I tried this and FDNs but didn't get anything thats really noise like 
from the start.


The reverb onset is always not very ideal.

Thats why some people suggset noise like FIRs for early reflections.

I dindt try this very much though cause reverb design is very time 
consuming, used reverbs I already had

maybe I have to look into this again.

Am 30.07.2016 um 19:20 schrieb Ethan Duni:

So like a cascade of allpass filters then?

Ethan D

On Fri, Jul 29, 2016 at 11:10 AM, gm > wrote:



I think what I am looking for would be the perfect reverb.

So that's the question reformulated: how could you construct a
perfectly flat short reverb?

It's the same problem.



Am 29.07.2016 um 12:18 schrieb Tito Latini:

An idea is to create a kind of "ideal" residual: i.e. the
transient is
a band-limited impulse and an enveloped (maybe expdec) noise
is added
after two, three or a few samples. The parameters are:

 - noise env
 - delay of the noise in samples
 - transient-to-noise ratio (% of transient, % of noise)

The transient (band-limited impulse) is spectrally flat and
the noise
adds the reverberation (you could start with a very low level).


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Re: [music-dsp] idealized flat impact like sound

[gm]

Am 30.07.2016 um 17:23 schrieb Tito Latini:

The other FIR's are not generally
allpass with all the possible input signals.

What a rip-off!./._  that box is not a "Perfectly Flat Short Reverb".


Yes I know... though I wasn't really aware untill recently tbh... ...

I actually tried synthesizing flat FIRs and wondered why it wasn't 
allpass... ...


So, alternativly a reverb with very dense modes that's percetptuall flat,
no fluctations on a larger scale.

Just a short sequence of random numbers really exhibits large formant 
like fluctuations .


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Re: [music-dsp] idealized flat impact like sound

[Ethan Duni]

So like a cascade of allpass filters then?

Ethan D

On Fri, Jul 29, 2016 at 11:10 AM, gm  wrote:

>
> I think what I am looking for would be the perfect reverb.
>
> So that's the question reformulated: how could you construct a perfectly
> flat short reverb?
>
> It's the same problem.
>
>
>
> Am 29.07.2016 um 12:18 schrieb Tito Latini:
>
>> An idea is to create a kind of "ideal" residual: i.e. the transient is
>> a band-limited impulse and an enveloped (maybe expdec) noise is added
>> after two, three or a few samples. The parameters are:
>>
>>  - noise env
>>  - delay of the noise in samples
>>  - transient-to-noise ratio (% of transient, % of noise)
>>
>> The transient (band-limited impulse) is spectrally flat and the noise
>> adds the reverberation (you could start with a very low level).
>>
>>
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Re: [music-dsp] idealized flat impact like sound

[Tito Latini]

> My problem was that a short segment of random isn't spectrally
> straigh-line flat.

My apologies, I've misunderstood the problem.

An idea is to create a kind of "ideal" residual: i.e. the transient is
a band-limited impulse and an enveloped (maybe expdec) noise is added
after two, three or a few samples. The parameters are:

- noise env
- delay of the noise in samples
- transient-to-noise ratio (% of transient, % of noise)

The transient (band-limited impulse) is spectrally flat and the noise
adds the reverberation (you could start with a very low level).
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Re: [music-dsp] idealized flat impact like sound

[gm]

I used both the minimum phase version of a band limited impulse and also 
the "empty" exp curve


the exp decay curve has more energy towards DC depending on its witdh 
but you dont hear that


like the "empty" exponential decay segment and dirac impulse the minimum 
phase pulse lacks reverberation and sounds very dry and liveless when 
you dont have soundboard model, even though it can extend quite long


but it has a quick rise time like 1ms and similar to the exp decay you 
can have a longer or shorter tail with more or less energy, and the 
onset shape is similar to an very quick real impact
there is not much difference in practice though to the decay curve, it's 
just one of the things I tried

it also makes a tiny chirp but you hardly hear that



Am 28.07.2016 um 22:49 schrieb Andy Farnell:

Following the comments regarding the exponential
modulated noise segment;

My experience is that all such actual segments will be
spectrally coloured, because of course they contain
a truncated set of random values.

The only theoretically "flat" exciter is the Dirac impulse.

But because it contains so little energy its not that
practical for stimulating waveguides.

Better to construct a band-limited pulse from a finite
set of sinusoids right up to the Nyquist.
A problem is this will have a finite rise time.

A practical compromise I found is to use the exponential
decay segment, as it is, without a payload, and make it
jolly short. I guess as T -> 0 the behaviour tends towards
the Dirac pulse, but where T is just a few tens of samples
it works as a very clean, reliable exitor for waveguides.
(Indeed this is what you have in a lot of analogue percussion
synthesis)

Perhaps someone can show you what the spectrum is as
a function of T, its not "flat" but its a good trade off
between a theoretically perfect impulse and a practical
signal.

cheers,
Andy

On Wed, Jul 27, 2016 at 07:00:02PM +0200, gm wrote:

Hi

I want to create a signal thats similar to a reverberant knocking or
impact sound,
basically decaying white noise, but with a more compact onset
similar to a minimum phase signal
and spectrally completely flat.

I am aware thats a contradiction.

Both, minimum phase impulse and fading random phase white noise are
unsatisfactory.
The minimum phase impulse does not sound reverberant.

The random phase noise isn't strictly flat anymore when you window
it with an exponentially decaying envelope
and also lacks a knocking impression.

I am also aware that a knocking impression comes from formants and
pronounced modes
related to shapes and material and not flat, which is another
contradiction..

I am not sure what the signal or phase alignment is I am looking for.

Also it's not a chirp cause a chirp sounds like a chirp.

What happens in a knock/impact besides pronounced modes or formants?
Somehow the phases are aligned it seems, similar to minimum phase
but then its
also random and reverberant.


Any ideas?



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Re: [music-dsp] idealized flat impact like sound

[Andy Farnell]

Following the comments regarding the exponential 
modulated noise segment;

My experience is that all such actual segments will be
spectrally coloured, because of course they contain
a truncated set of random values.

The only theoretically "flat" exciter is the Dirac impulse.

But because it contains so little energy its not that
practical for stimulating waveguides.

Better to construct a band-limited pulse from a finite 
set of sinusoids right up to the Nyquist.
A problem is this will have a finite rise time.

A practical compromise I found is to use the exponential
decay segment, as it is, without a payload, and make it
jolly short. I guess as T -> 0 the behaviour tends towards
the Dirac pulse, but where T is just a few tens of samples
it works as a very clean, reliable exitor for waveguides.
(Indeed this is what you have in a lot of analogue percussion
synthesis)

Perhaps someone can show you what the spectrum is as
a function of T, its not "flat" but its a good trade off
between a theoretically perfect impulse and a practical 
signal.

cheers,
Andy

On Wed, Jul 27, 2016 at 07:00:02PM +0200, gm wrote:
> 
> Hi
> 
> I want to create a signal thats similar to a reverberant knocking or
> impact sound,
> basically decaying white noise, but with a more compact onset
> similar to a minimum phase signal
> and spectrally completely flat.
> 
> I am aware thats a contradiction.
> 
> Both, minimum phase impulse and fading random phase white noise are
> unsatisfactory.
> The minimum phase impulse does not sound reverberant.
> 
> The random phase noise isn't strictly flat anymore when you window
> it with an exponentially decaying envelope
> and also lacks a knocking impression.
> 
> I am also aware that a knocking impression comes from formants and
> pronounced modes
> related to shapes and material and not flat, which is another
> contradiction..
> 
> I am not sure what the signal or phase alignment is I am looking for.
> 
> Also it's not a chirp cause a chirp sounds like a chirp.
> 
> What happens in a knock/impact besides pronounced modes or formants?
> Somehow the phases are aligned it seems, similar to minimum phase
> but then its
> also random and reverberant.
> 
> 
> Any ideas?
> 
> 
> 
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Re: [music-dsp] idealized flat impact like sound

[gm]

My problem was that a short segment of random isn't spectrally 
straigh-line flat.


If you feed this into a resonator (waveguide) you can hear a difference 
between one random grain and another with another random sequence.


This is usally a desired effect that makes the sound alive,
but in my case I wanted to eliminate this for then moment.

And it doesnt help to synthesize a flat random sequence with FFT since it's
not flat after evenveolping/windowing.

I managed to get a flatter response the follwing way:

create a segment of exp decay padded with silence
repeat:
 FFT (of double size) and set all magnitudes to 1
 iFFT
 set second half of time signal to zero
/repeat

it seems to converge to a flat aproximately exponentially decaing signal
(I have only done 20 or so iterations manually so I am not sure how it 
behaves)


Dont ask me why, maybe its just a simple genetic algorithm thing

The result is a little bit strange however, slightly metallic
and when you convolve it with it self several times you get some kind of 
multichirp soundwise
where sparse narrow dips and phase delay appears at random places across 
the spectrum


Similar to a spring or allpass chain but with multiple random "resonances"


Am 28.07.2016 um 19:17 schrieb Tito Latini:

sorry, that's a decay, so out is "(1 - y) * rand()":

T = 1 / samplerate
p = exp(log(0.001) * T / t60)

y = 1 + p*(y1 - 1)
y1 = y
out = (1 - y) * rand(-1.0, 1.0) * gain
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Re: [music-dsp] idealized flat impact like sound

[Tito Latini]

sorry, that's a decay, so out is "(1 - y) * rand()":

T = 1 / samplerate
p = exp(log(0.001) * T / t60)

y = 1 + p*(y1 - 1)
y1 = y
out = (1 - y) * rand(-1.0, 1.0) * gain
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Re: [music-dsp] idealized flat impact like sound

[Tito Latini]

On Wed, Jul 27, 2016 at 10:33:40PM +0200, gm wrote:
> [...]
> So my question for now is: how can we synthesize completely flat 
> decaying noise?
> (is it even possible?)

I think the modulation between expdec and white noise is ok:

T = 1 / samplerate
p = exp(log(0.001) * T / t60)

y = (1 - p)*gain + p*y1
y1 = y
out = y * rand(-1.0, 1.0)
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Re: [music-dsp] idealized flat impact like sound

[Ross Bencina]

On 28/07/2016 3:00 AM, gm wrote:

I want to create a signal thats similar to a reverberant knocking or
impact sound,
basically decaying white noise, but with a more compact onset similar to
a minimum phase signal
and spectrally completely flat.


Maybe consider mixing multiple signals together: e.g. a bandlimited 
impulse for the attack, plus something else for the tail.


You might consider the variant of the Karplus-Strong algorithm for drum 
synthesis. Not the original source, but I found a description here:


https://ccrma.stanford.edu/~sdill/220A-project/drums.html#ks

Ross.
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Re: [music-dsp] idealized flat impact like sound

[David Reaves]

What you are describing sounds a bit like a description of thunder: a sharp, 
wideband pulse followed by reverberant randomness, (though not spectrally flat 
due to environmental absorption).
Perhaps you can use that as a model?

David Reaves
Recklinghausen, Germany


On Wed, 27 Jul 2016 19:00:02 +0200, gm  wrote:

> Hi
> 
> I want to create a signal thats similar to a reverberant knocking or 
> impact sound,
> basically decaying white noise, but with a more compact onset similar to 
> a minimum phase signal
> and spectrally completely flat.
> 
> I am aware thats a contradiction.

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Re: [music-dsp] idealized flat impact like sound

[gm]

(Hi Matt, we've met before at NI btw, briefly)

Thanks, I look these up, I think I browsed through some of this a few 
years ago, Rocchesso I think.


I already had a hammer model for the same thing, which is piano synthesis
and a soundboard model.

For the moment I am more interested in spectral flatness.
I would like to synthesize decaying white noise thats completely flat
Basically the ideal reverb response in a way.

I want to figure out what details make a piano sound sound like piano, 
and how to exaggerate or idealize these
thats one reason why I replaced hammer model and soundboard model with 
white noise for now.


(It turns out that the fluctuations in the spectrum matter, but can also 
give an interesting touch

when the noise varies with time...)

Now I want to replace it with something really flat to figure out what
role some of the modes of different real soundboards have, if any, or if 
the impact sound is more important (if it is)
and what makes that impact, perceptionally, in the case of the piano 
(where immediate collision sounds don't matter).


I also experimented with random phase noise of the soundbard spectrum vs 
the recorded impact
It makes a difference but I am not sure what it is at the moment, 
perceptionally and phase wise.
A minmum phase version of the same impact seems to sound worse to me for 
instance.

The reverberation seems quite important.

An other thing thats of importance seem to be the reflections between 
hammer

and where the string is fixed, but you dont need an impact model for this,
they can be modeled with a truncated comb filter response... thats 
already seperated out.


So my question for now is: how can we synthesize completely flat 
decaying noise?

(is it even possible?)


Am 27.07.2016 um 21:33 schrieb Matt Jackson:

There might also be something by max Matthews or Curtis Roads.
I think I recall a chapter in the computer music tutorial.

Sent from a phone.


On 27.07.2016, at 20:47, Andy Farnell  wrote:

For impact/contact exciters you will find plenty
of empirical studies and theoretical models in the
literature by;

Davide Rocchesso
Bruno Giodano
Perry Cook

These are good initial paper authors to search

all best
Andy Farnell




On Wed, Jul 27, 2016 at 07:00:02PM +0200, gm wrote:

Hi

I want to create a signal thats similar to a reverberant knocking or
impact sound,
basically decaying white noise, but with a more compact onset
similar to a minimum phase signal
and spectrally completely flat.

I am aware thats a contradiction.

Both, minimum phase impulse and fading random phase white noise are
unsatisfactory.
The minimum phase impulse does not sound reverberant.

The random phase noise isn't strictly flat anymore when you window
it with an exponentially decaying envelope
and also lacks a knocking impression.

I am also aware that a knocking impression comes from formants and
pronounced modes
related to shapes and material and not flat, which is another
contradiction..

I am not sure what the signal or phase alignment is I am looking for.

Also it's not a chirp cause a chirp sounds like a chirp.

What happens in a knock/impact besides pronounced modes or formants?
Somehow the phases are aligned it seems, similar to minimum phase
but then its
also random and reverberant.


Any ideas?



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Re: [music-dsp] idealized flat impact like sound

[Matt Jackson]

There might also be something by max Matthews or Curtis Roads. 
I think I recall a chapter in the computer music tutorial. 

Sent from a phone. 

> On 27.07.2016, at 20:47, Andy Farnell  wrote:
> 
> For impact/contact exciters you will find plenty 
> of empirical studies and theoretical models in the 
> literature by;
> 
> Davide Rocchesso
> Bruno Giodano
> Perry Cook
> 
> These are good initial paper authors to search 
> 
> all best
> Andy Farnell
> 
> 
> 
>> On Wed, Jul 27, 2016 at 07:00:02PM +0200, gm wrote:
>> 
>> Hi
>> 
>> I want to create a signal thats similar to a reverberant knocking or
>> impact sound,
>> basically decaying white noise, but with a more compact onset
>> similar to a minimum phase signal
>> and spectrally completely flat.
>> 
>> I am aware thats a contradiction.
>> 
>> Both, minimum phase impulse and fading random phase white noise are
>> unsatisfactory.
>> The minimum phase impulse does not sound reverberant.
>> 
>> The random phase noise isn't strictly flat anymore when you window
>> it with an exponentially decaying envelope
>> and also lacks a knocking impression.
>> 
>> I am also aware that a knocking impression comes from formants and
>> pronounced modes
>> related to shapes and material and not flat, which is another
>> contradiction..
>> 
>> I am not sure what the signal or phase alignment is I am looking for.
>> 
>> Also it's not a chirp cause a chirp sounds like a chirp.
>> 
>> What happens in a knock/impact besides pronounced modes or formants?
>> Somehow the phases are aligned it seems, similar to minimum phase
>> but then its
>> also random and reverberant.
>> 
>> 
>> Any ideas?
>> 
>> 
>> 
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Re: [music-dsp] idealized flat impact like sound

[Andy Farnell]

For impact/contact exciters you will find plenty 
of empirical studies and theoretical models in the 
literature by;

Davide Rocchesso
Bruno Giodano
Perry Cook

These are good initial paper authors to search 

all best
Andy Farnell



On Wed, Jul 27, 2016 at 07:00:02PM +0200, gm wrote:
> 
> Hi
> 
> I want to create a signal thats similar to a reverberant knocking or
> impact sound,
> basically decaying white noise, but with a more compact onset
> similar to a minimum phase signal
> and spectrally completely flat.
> 
> I am aware thats a contradiction.
> 
> Both, minimum phase impulse and fading random phase white noise are
> unsatisfactory.
> The minimum phase impulse does not sound reverberant.
> 
> The random phase noise isn't strictly flat anymore when you window
> it with an exponentially decaying envelope
> and also lacks a knocking impression.
> 
> I am also aware that a knocking impression comes from formants and
> pronounced modes
> related to shapes and material and not flat, which is another
> contradiction..
> 
> I am not sure what the signal or phase alignment is I am looking for.
> 
> Also it's not a chirp cause a chirp sounds like a chirp.
> 
> What happens in a knock/impact besides pronounced modes or formants?
> Somehow the phases are aligned it seems, similar to minimum phase
> but then its
> also random and reverberant.
> 
> 
> Any ideas?
> 
> 
> 
> ___
> dupswapdrop: music-dsp mailing list
> music-dsp@music.columbia.edu
> https://lists.columbia.edu/mailman/listinfo/music-dsp
> 


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[music-dsp] idealized flat impact like sound

[gm]

Hi

I want to create a signal thats similar to a reverberant knocking or 
impact sound,
basically decaying white noise, but with a more compact onset similar to 
a minimum phase signal

and spectrally completely flat.

I am aware thats a contradiction.

Both, minimum phase impulse and fading random phase white noise are 
unsatisfactory.

The minimum phase impulse does not sound reverberant.

The random phase noise isn't strictly flat anymore when you window it 
with an exponentially decaying envelope

and also lacks a knocking impression.

I am also aware that a knocking impression comes from formants and 
pronounced modes
related to shapes and material and not flat, which is another 
contradiction..


I am not sure what the signal or phase alignment is I am looking for.

Also it's not a chirp cause a chirp sounds like a chirp.

What happens in a knock/impact besides pronounced modes or formants?
Somehow the phases are aligned it seems, similar to minimum phase but 
then its

also random and reverberant.


Any ideas?



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