I am always searching for new combination of sounds to run as the source and impulse in a convolution plugin. I'm not looking for reverbs so much as cool sfx.

I once heard a flame whoosh sent through a glass breaking and it ended up sounding ice fireball! Got any good suggestions? Do you have better success with shorter longer impulses? Recorded sounds or synth tones?

6 Answers 6


One aspect to remember is that convolution reinforces the frequencies that the source & IR have in common.... I've bought a few collections of IRs and it can be quite interesting listening to just the IRs, apart from delays & reverbs some more stylised IRs are quite harmonically dense and I think this is why - if the IR has a lot of interesting frequency content then it will 'bring out' many frequencies in the source file.... Convolve violins & thunder and you probably won't get much, but who knows - the 'not much' part may be very interesting! I recorded a group of people whispering in an ADR studio years ago & its been useful a few times eg making wind gusts whisper etc....

  • Hi Tim, thanks for the post. Tried replicating your "whispering wind gust" today with not much success, perhaps my whispering files were too long? Ended up with more tonality than "whisper" movement, if that makes sense. Working with Altiverb and exporting .wavs from Pro Tools. Interested to know your approach - Mar 16, 2010 at 4:35
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    +1 on unauthorized misuse of IR's. Using a bowed cymbal as an IR is pretty sick. Mar 17, 2010 at 4:10

Try everything and anything - you never know what sounds will react with each other in interesting ways. I've had good luck with metal impacts, such as light taps on thin and thick metal, large hits inside of an oven, and cooling racks. Glass is good as well, such as light dings on regular glass, crystal bowls or large jars.

This is also a great way to experiment with sound design ideas since it's very easy to execute, depending on your convolution engine/software. With Altiverb, for example, all you need to do is make sure to append the correct suffix on your sound file, drop it in the folder hierarchy, and you're good to go.


Check: http://www.spiritcanyonaudio.com/index.php

Those guys have lots of great impulse responses collection with lots of different approaches.


It really depends on the kind of sound effect you are trying to create. As a general rule, longer impulses are better for creating ambiences and soundscapes but, having said that, if you take a very short sound and convolve it with a long impulse you might get an interesting spot effect. It all depends on the spectra and length of the two sounds you're convolving and what you're hoping to get. I've found that convolution using exotic impulses is very good for producing ghostly, breathlike effects, stingers and dark ambiences.

The "Pulses" folder in Virtuasonic's impulse library called Synesthesis comprises very short impulses that produce interesting effects. Stacking impulses can also produce interesting results, particularly short following long or vice versa.

The whole process of unconventional convolution is somewhat alchemical and the results can be unpredictable unless you've got a good sense of pitch and what musical notes equate to on a spectrograph. Some rules of thumb are:

the longer the impulse you're using, the greater the smear or blur that will be imparted to your sound.

Prominent frequency components in either the impulse or the audio you wish to treat will be preserved, so if you have a very musical impulse, your audio will most likely take on those qualities. If you are treating a piece of music then long notes in particular will be preserved in some form.

Frequency sweeps used as impulses will produce frequency dependent delays. Sound effects used as impulses faded in or faded out will produce reverse reverb qualities and reverb qualities respectively.

Here's an excelent article from Electronic Musician that goes into a lot of detail on how to get the most out of convolution.


  • I've had very interesting results doing this as well. Be careful though because this can produce a lot of resonance depending on the audio files you're using. This is also true if you apply the same impulse to a piece of audio more than once. It's always a good idea when playing around with unconventional convolution to take even more care with your monitoring levels and watch out for clipping. Jul 19, 2010 at 22:46

I like to play around with TL Space's "Effects" IRs, although they can be hit and miss - sometimes it ends up only sounding like the IR sample itself, while other times it can create interesting results.

For "Design Reverb" two of my favorite go-to's are TL Space's Infinite 1 and Infinite 2 in the Digital reverb section (the image of the IR Sample shows images of the Mars Rover).

As for selecting your own source, it's not something that I have had much of an opportunity to try aso much under my normal time constraints. Wave's IR1 has the ability to import WAV files for IRs, but I've not had much success (for some reason the L/R volumes are mismatched once they're inported into the IR1).


Try using the same audio file as both the impulse response and the sound being processed. I had good results using this on a glass smash - turned a single impact into a large shower!

Could be interesting to try this technique on a range of sounds, varying parameters of your reverb plugin.

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