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?
_______________________________________________
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp
_______________________________________________
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp
_______________________________________________
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp
