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The click~ object and band limited impulses…

October 10, 2007 | 6:14 pm

I’m a complete beginner when it comes to this area so please bear with me on this one.

I understand that the click~ object is an impulse generator.

So…

Are impulses related to band limited impulses and how would I go about creating a band limited impulse using the click object if this were the case?

Many thanks,

Rhys


October 10, 2007 | 9:39 pm

ok…. what are you trying to do?. It depends what you mean by an
impulse. It is a generic term that can be used to describe an
extremely short burst of sound or an acoustic signature of a an
architectural space (and more) which you can use to re-create its
reverberant qualities.

Historically, an Impulse generator could be seen as one of the first
microsonic (Microsound by Curtis Roads) generators. The generator
creates sounds of very short duration which because of their short
duration generate a wide spectrum, which can then be filtered to
create a variety of timbres.

It might be worth looking at a electro-acoustic primer or something
like the "Microsound" Book by Curtis Roads, which is a great read. If
it is about convolution then it might be worth experimenting with some
of the convolving reverbs around. I remember an msp object which did
this (?).

P

On 10/10/2007, Rhys Perkins wrote:
>
> I’m a complete beginner when it comes to this area so please bear with me on this one.
>
> I understand that the click~ object is an impulse generator.
>
> So…
>
> Are impulses related to band limited impulses and how would I go about creating a band limited impulse using the click object if this were the case?
>
> Many thanks,
>
> Rhys
>


Pere Josep Villez
Creative and Computational Sound
Department of Creative Technologies
University of Portsmouth
36-40 Middle Street
Portsmouth
PO5
Tel 00 44 23 9284 8484

http://www.centuryofnoise.com
http://www.perevillez.com


October 10, 2007 | 10:00 pm

If I understand your question (or, perhaps, the intent behind it) a
‘perfect’ impulse would theoretically contain equal energy across the
frequency spectrum of human hearing. A band-limited impulse is simply
an impulse which has some portion (often the high end) of its
frequency spectrum attenuated or eliminated altogether. In a digital
system a single-sample at full amplitude is the closest you can get
to the ‘perfect’ impulse – this is essentially what [click~] produces
by default. You can be creative about how you limit/modify the
bandwidth using any of the array of available filters on the output
of [click~].

For some relevant reading, check out some of the following:

< http://ccrma.stanford.edu/~jos/pasp/Commuted_Piano_Synthesis.html>
<
http://ccrma.stanford.edu/~jos/filters/Impulse_Response.html>
<
http://www.daqarta.com/dw_0a0i.htm>
<
http://www.dspguide.com/ch19/2.htm>
<
http://www.dspguru.com/info/faqs/fir/basics.htm>
<
http://en.wikipedia.org/wiki/Impulse_response>
<
http://www.dspguide.com/ch6.htm>

On Oct 10, 2007, at 12:14 PM, Rhys Perkins wrote:

>
> I’m a complete beginner when it comes to this area so please bear
> with me on this one.
>
> I understand that the click~ object is an impulse generator.
>
> So…
>
> Are impulses related to band limited impulses and how would I go
> about creating a band limited impulse using the click object if
> this were the case?
>

—-
Steven M. Miller
Professor, Contemporary Music Program
College of Santa Fe

Home < http://pubweb.csf.edu/~smill>
SFIFEM <
http://sfifem.csf.edu>
Atrium Sound Space <
http://atrium.csf.edu>
OVOS <
http://pubweb.csf.edu/~smill/ovos.html>
CMP <
http://www.csf.edu/csf/academics/cmp/index.html>


October 10, 2007 | 10:02 pm

This is more correctly referred to as the ‘impulse response’ of the
room (or algorithm, or circuit, or…), not the impulse itself.

On Oct 10, 2007, at 3:39 PM, Pere Josep Villez wrote:

> or an acoustic signature of a an
> architectural space (and more) which you can use to re-create its
> reverberant qualities.

—-
Steven M. Miller
Professor, Contemporary Music Program
College of Santa Fe

Home < http://pubweb.csf.edu/~smill>
SFIFEM <
http://sfifem.csf.edu>
Atrium Sound Space <
http://atrium.csf.edu>
OVOS <
http://pubweb.csf.edu/~smill/ovos.html>
CMP <
http://www.csf.edu/csf/academics/cmp/index.html>


October 11, 2007 | 11:25 am

Where did the links go?

> For some relevant reading, check out some of the following:

Thanks

Rhys



October 12, 2007 | 1:59 pm

—————————————————-
> You can be creative about how you limit/modify the
> bandwidth using any of the array of available filters on the output
> of [click~].

how do you bandlimit a spike? that is always an interesting question.

well, lets say someone has a wavetable synth or an impulse train he needs to bandlimit … i am tempted to say such a wave can be bandlimited the same way than you would do it to any other wave.

for a synthesizer oscillator you have several options of course, normally you would try to calculate harmonic waves already bandlimited, and not filter your audio when its already there.

but the most simple way for already given waves (please correct me if thats wrong) would be a sample interpolation filter with exponential interpolation such as [slide~ 2.0001 2.0001].

of course the slide filter would hav to be "tuned" in case we are talking about a pulse train "oscillator" … "2.0" only works for the "base note" …

otoh, as son as you know how a bandlimted spike looks, you can use the [click~] object to output that directly; its perfect for such things.


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