Thanks to great plugins like Altiverb, Reveberate, TL Space etc you will no doubt be aware of the use of Impulse Responses to recreate the reverberation of acoustic spaces such as concert halls, churches etc..
And for post production IRs are invaluable for recreating real world environments, to match ADR into production sound and to simulate for example, sounds from next door apartment, inside vehicles etc…
But what if you want to put ‘lightning in a bottle?’
My first experience with the idea of using IRs captured from within small objects came from Claustrophobia, an IR set recorded & released by Fokk van Saane. Back in 2004 while working on the horror film Boogeyman, I needed to create sound for an occasionally evil plasma ball. After syncing and manipulating electrical sounds the final aspect that set my sounds into the plasma ball was the use of a small glass object IR. The glass resonance was imparted on my sounds and sold the reality of the sound design. Ever since I have wanted to explore this territory further, and it was only when collecting and recording props for the glass sound FX libraries that I decided to pursue it.
This collection of GLASS Object Impulse Responses contains five specific approaches:
- 32 Empty Glass Object IRs were captured using an MKH8020 mic. The two yard glasses (& other narrow neck bottles) were captured using a DPA4060 mic. These objects can be thought of as a tiny concert hall, with small scale room modes and peaky resonance with a glassy tone. The IRs tend to be short and high frequency, with the total volume and the size of the neck contributing to their sound.
- Pitch shifted IRs at half speed & quarter speed. As with all convolution, frequencies that are common to the source and the IR are accentuated, for example if you convolve a sub bass sound with a violin you get nothing. So as an experiment I tried pitch shifting the 32 Glass Object IRs, and at both half speed and quarter speed the spectrum of the resonance is lowered into potentially useful range, and is of course elongated. Lowering the pitch expands the potential applications for these IRs.
- Underwater IRs Next each of the objects were filled with water and underwater IRs were captured using a hydrophone. As water is denser than air, the speed of sound is faster which equates to higher frequency, faster reflections and strangely harmonic ringy IRs. Pitch shifted underwater IRs at half speed & quarter speed are also included.
- Jelly IRs. Three of the objects were filled with jelly, and IRs were captured with the hydrophone set in the jelly. Pitch shifted Jelly IRs at half speed & quarter speed are also included.
- Iterated IRs. While working on this collection I was reminded of the fascinating work by Alvin Lucier – I Am Sitting In A Room, where Lucier played a recording of his voice into a room, captured the room sound and then replayed it into the room, again recording it. As the process is repeated again and again, the dialogue becomes entirely unintelligible as the iterated room acoustic slowly became a harmonic drone. Listen to Luciers work here
To achieve this with an IR, I iterated the process playing the captured IR back into the object. As a test, I iterated ten times and found the IRs rapidly became diffuse and accentuated tonal resonance, with blurred transients. Some iterated IRs almost sounding like harmonic feedback while others latched on to low frequencies. Based on the results I decided to include the first and third iterations.
In total this collection contains 345 Impulse Responses, please check the file list below.
To provide a quick insight to how these IRs sound in use, I have processed a few different source sounds with each IR: A beat played on drumkit and some inane dialogue DX. Each example sound is first played unprocessed, then cycles through real speed IR, half speed IR and quarter speed IR.
Also Note: Presets for Logic Space Designer are now included, to allow faster browsing and audition!
These IRs have been tested in the following Convolution plugins.
AudioEase Altiverb – check their great Pipe IRs video
Apple Space Designer – Logic or Mainstage
Ableton Convolution Reverb
Melda Production MConvolutionEZ (free)
Impulse Record Convology XT (free)
Please check the manual for your specific IR plugin to verify where these custom IRs should be stored.