Impulse Response audio files
Fichiers audio à réponse impulsionnelle


Some free impulse responses (IRs) to download !
Quelques IRs gratuits à télécharger !



File Name

Altiverb™ - sit
package format

48 KHz - 24 bit
96 KHz - 24 bit

Audio - wav
48 KHz - 24 bit
48 KHz - 32 bit
96 KHz - 24 bit
96 KHz - 32 bit

Example - mp3
convolved with
a drum sequence

128 Kb/s


Big Hall E001 M2S
Big Hall E002 M2S
Big Hall E003 M2S
Mini Caves E001 M2S
      598 KB
      1'750 KB
      1'943 KB
      343 KB
      680 KB
      4'091 KB
      4'596 KB
      590 KB

112 KB
287 KB
331 KB
110 KB


DubWise E001 M2S
Filterverb E001 M2S
Gated Place E001 M2S
Small Church E001 M2S
      1'103 KB
      544 KB
      239 KB
      441 KB
      1'726 KB
      565 KB
      148 KB
      580 KB

174 KB


Flangerspace E001 M2S
Mega Diffusor E001 M2S
Corridor Flutter Echo E001 M2S
Medium Metal Room E001 M2S
      158 KB
      2'174 KB
      215 KB
      966 KB
      81 KB
      3'260 KB
      593 KB
      2'647 KB



Pipe & Carpet E001 M2S
Damped Cave E001 M2S
Damped Cave E002 M2S
Damped Cave E003 M2S
      470 KB
      1'972 KB
      1'605 KB
      2'176 KB
      1'170 KB
      10'845 KB
      11'253 KB
      11'255 KB



Damped Cave E004 M2S
Damped Cave E005 M2S
High Damping Cave E001 M2S
Large Damping Cave E001 M2S
      2'342 KB
      2'148 KB
      459 KB
      992 KB
      11'255 KB
      11'255 KB
      1'945 KB
      7'696 KB



Medium Damping Cave E001 M2S
Medium Damping Cave E002 M2S
Medium Damping Room E001 M2S
      469 KB
      748 KB
      604 KB
      667 KB
      1'319 KB
      3'063 KB



      789 KB
      353 KB
      805 KB
      489 KB



      938 KB
      870 KB
      1'017 KB
      1'012 KB



      169 KB
      273 KB
      51 KB
      302 KB



WIDE HALL-1       1'770 KB       2'737 KB




What is convolution
Convolution is the effect of multiplying every sample in one wave or impulse by the samples that are contained within another waveform. In a sense, this feature uses one waveform to “model” the sound of another waveform. The result can be that of filtering, echoing, reverberating, phase shifting, or any combination of these effects.

For example, “convolving” someone saying “Hey” with a drum track (short full spectrum sounds such as snares work best) will result in the drums saying “Hey” each time they are hit.
With the proper impulses, any reverberant space can be simulated. For example, if you have an impulse of your favorite cathedral, and convolve it with any audio, then the result would sound as if that audio were played in that cathedral.
You can generate an impulse like this by going to the cathedral in question, standing in the spot where you would like the audio to appear it is coming from, and generating a loud impulsive noise, like a “snap” or loud “click”. You can make a stereo recording of this “click” from any location within the cathedral. If you used this recording as an impulse, then convolution with it will sound as if the listener were in the exact position of the recording equipment, and the audio being convolved were at the location of the “click”.

What is an impulse response file
An “impulse response file” is the data by which every other sample in your waveform will be multiplied. If the impulse is a single sample of a full volume “tick”, then the convolution of that impulse with any audio data will just be that audio data itself. If that “tick” is at half volume, then the original audio data will be reproduced at half volume.

If there are several ticks, descending in amplitude over time, such as one tick every 100 milliseconds, and half as loud as the previous tick (fig. 2), then the result of convolution (fig. 3) with some audio (fig. 1) will be that sound echoed with 100ms between each echo, and each echo at half the volume of the previous echo.

fig. 1

fig. 2

fig. 3

Another interesting use for convolution is to generate an infinite sustained sound of anything. For example, one singing “aaaaaah” for one second could be turned into thousands of people singing “aaaaaah” for any length of time by using some white noise.

Example 1 Source : snare drum
ex1_src1.wav 36 KB
Impulse : 100 ms spaced decaying tics
ex1_imp1.wav 69 KB
Convolution result :
ex1_res1.wav 82 KB
Example 2 Source : man voice
ex2_src2.wav 454 KB
Impulse : Metallic delay effect
ex2_imp2.wav 517 KB
Convolution result :
ex2_res2.wav 1'165 KB
Example 3 Source : snare drum
ex1_src1.wav 36 KB
Impulse : 4 s decaying white noise
ex3_imp3.wav 690 KB
Convolution result :
ex3_res3.wav 760 KB

To get a feel of convolution, load up and play with some of the sample Impulse files on this page using your favorite hardware or software convolver.
Enjoy !

A bit more about convolution
Imagine the following example :
An audio file containing 8 samples (X
0 to X7) convolved with an impulse file containing 4 samples (i0 to i3).
That would give the following table :

Source file samples (Xn)









Impulse file samples (ik)






i0 X0

i0 X1

i0 X2

i0 X3

i0 X4

i0 X5

i0 X6

i0 X7


i1 X0

i1 X1

i1 X2

i1 X3

i1 X4

i1 X5

i1 X6

i1 X7


i2 X0

i2 X1

i2 X2

i2 X3

i2 X4

i2 X5

i2 X6

i2 X7


i3 X0

i3 X1

i3 X2

i3 X3

i3 X4

i3 X5

i3 X6

i3 X7

This can be represented by the following diagram :

Which correspond to the following expression :

Y(n) = i0 · X(n) + i1 · X(n-1) + i2 · X(n-2) + i3 · X(n-3) + ... + ik · X(n-k)

Or to the following general equation :