Is there a way to simulate Larsen effect (audio feedback) with PD?

audio feeback? easy.

you just send your signal into a [delwrite~] object, and then send it back out through a [delread~] object

and then multiply your signal by 95% (or something between 90-99%)

and then send it back into the [delwrite~] object

this makes a feedback loop, in which the sound is degraded about 5% each pass.

Thanks.
But, I'm not sure this is a good simulation of Larsen effect
(i.e. the howl you hear when you move a microphone too close to a loudspeaker).
There should be something more than a delay with feedback, I guess.
If you have any idea, please let me know.

Putting a mic to close to a loudspeaker is like setting up a comb filter. If you set delay of the delread~ around 3-30 ms, and multiply the signal by 95-100 (like hardoff sez) then you should get similair feedback.

well, the thing is with the microphone and the speaker is that all sorts of pitch shifting effects, reverb effects and stuff like that are going to occur, due to conditions in the room and sound system. also, the microphone is never at exactly the same distance from the speaker, cos your body is moving if you are holding it....same thing with a guitar.

sorry rcoco....i didn't realise that you were looking for something so "genuine" in its sound.

maybe read up on the larson effect, and figure out what the main components are, and then add those components to your patch.

i doubt that someone has already written an external for this, but i think there might be some vst plugins that can make a fairly good feedback sound. can you use vst~ with your computer though? i can't cos i'm on a mac. ...i wish someone would hurry up and port the vst~ object to work here.

Hardoff sez:

well, the thing is with the microphone and the speaker is that all sorts of pitch shifting effects, reverb effects and stuff like that are going to occur, due to conditions in the room and sound system. also, the microphone is never at exactly the same distance from the speaker, cos your body is moving if you are holding it....same thing with a guitar.

And I reply:

Yeah, it's the tough part of the digital realm. You have to take all these factors that are so easy to produce in the real world (ie put a mic close to it's reciever) and seperate them into discreet components that we can work with. So what we have:

The comb filter set up by the mic's proximity to the reciever. The distance is constantly changing, and since v=f(lamda), then the feedback coefficient and the delay time need to have miniscule variation. if you use vd~ rather than delread~ , you can add noise~ (*~ a small value) to your sig~ and get a comb filter that mimics the realworld elements.

...or you could just get a microphone and put it in front of a speaker.

i have never really understood the fascination some people have with re-creating real-world events in a digital environment.

Thank you for the suggestions.
I was trying to re-create with PD the environment of "Pendulum Music" by Steve Reich; it's just an exercise for my computer music course.