We came across this free library of impulse responses collected across a range of heritage spaces at Chatham Dockyard in Kent, UK. What grabbed our attention is that although these impulse responses are from a historical site they offer a wide range of spaces that can be used in a wide variety of applications as well as some difficult-to-get spaces like a submarine or air-raid shelter. If you need to recreate spaces in your sound design or audio post-production work, do check these out.

The Location

Chatham Dockyard was a working shipyard for 500 years, from the age of sailing ships to nuclear-powered submarines. The site is now a museum and its historic buildings regularly feature in films and on television.

This library has been created as part of the University of Kent’s AHRC-funded research into the potential of sound to contribute to heritage experiences and reveal new narratives about the past.

What Is Included In This Free Library?

Impulse Responses have been captured in seven different locations across Chatham Dockyard. Once you download the library you will find that each location has its own folder of impulse responses:

Please note that the impulse responses were recorded using a variety of different microphone types and setups. Each location has been sampled from a range of different perspectives and microphone types.

• DPA 4061 – Stereo – Omnidirectional small capsule condenser microphones

• Neumann KM184 – Stereo – Cardioid condenser microphones

• Soundfield ST450 – 1st Order Ambisonics (B-Format; Decoded to Binaural and Stereo)

Not only will the frequency response of each microphone vary, but the perspective and location from the sound source will change subtly too. Therefore, each set will have a slightly different spatial position in relation to the impulse source.

Different microphone types will capture subtly different features of the environment. Omnidirectional IRs may have slightly better frequency response, while Cardioid may be more responsive in terms of time (i.e. have a sharper transient response).

Ambisonic recordings have also been used to create IR files in Binaural and Stereo.

N.B. Not all sites contain full microphone setups, as it was not always possible to record with all the microphone arrays in every location.

The Locations

What Is An Impulse Response?

Impulse Responses are used within Reverb plugins to simulate the sound of spaces. Any sound can be blended with any Impulse Response, creating a new output that combines the characteristics of both.

For example, a voice (recorded in the studio) can be combined with the Impulse Response of a specific room, to create the impression that the person is actually speaking in that other space.

Where Do Impulse Responses Come From?

An Impulse is played into the space to activate the acoustics and reveal its reverberant character. Its response is captured using standard microphones and the recording (impulse + space) is later processed to leave only the recorded trace of the space. There are two different ways to make an impulse response, either with a Burst or a Sweep.

Impulse Types – Burst or Sweep

Impulses can be captured using either short bursts of noise, or longer sine tone sweeps that rise from low to high. Both give you an image of the reflections in a space.

Noise bursts give you a momentary snapshot of the reverberation in a space and are quick to record, but don’t always contain so much detail across the spectrum (especially the lower frequencies).

Sine sweeps give a more detailed gradual scan of the acoustic at the full range of different frequencies (the slower the sweep the better the resolution) but they can be more challenging to record. These sweeps also need to be converted before they can be used.

How To Use These Impulse Response Libraries

There are lots of different tools and programmes which will accept Impulse Responses. There are two versions available…

1. Sonic Palimpsest Impulse Response Library

   • Contains deconvolved .wav impulse files, which can be imported into a wide range of different Convolution Reverb plugins.

   • Check the manual of your plugin for details on how to import our IR Library.

2. Sonic Palimpsest – Altiverb IR Library

   • Altiverb is a Convolution Reverb plugin from Audio Ease. Their plugin uses some custom coding to convert the IRs and import them to a proprietary format for use with Altiverb.

   • If you have a copy of Altiverb, you can add these precompiled impulse response library directly into Altiverb by copying the files to the following destination: Applications/Audio Ease/Altiverb 7/Impulse Responses/Third Party IR Libraries

Usage Limitations

Anyone can download and use these impulse response files to experience what it is like to sound within the acoustic environments of these unique historic spaces. You might also choose to creatively use the sounds of these spaces within musical compositions or film sound design and post-production, adding unique sound spaces to your projects.

Download Impulse Response Libraries

What We Think Of The Sonic Palimpsest Impulse Response Library

This is a really useful set of impulse responses for use in sound design and audio post-production, as an interesting collection of real spaces. We don’t always get impulse responses for the spaces used in the projects we work on. This free collection of impulse responses, although collected for historical reasons, provides a really useful resource of impulse responses of some very interesting spaces, than can be used for a wide range of applications.

For example the covered slip could be used for a large wooden barn, or timber framed performance space. The air-raid shelter can be used for all kinds of restricted spaces, perhaps even inside a washing machine! The rooms in the Commissioners House would be great for any period drama.