What is Ambisonics?

OK, so I said in my first blog post that I’m hoping to mix the tracks using Ambisonics so I guess I’d better explain what that means. I’ll try and keep away from too much technical jargon and just explain what it is, where it’s from and why I want to use it.

Ambisonic is a spatial audio technique used over a loudspeaker array (generally four or more loudspeakers, though it can collapse to stereo) to place a sound in space. It is a periphonic technique, which means sounds can be placed anywhere in a sphere around a listener (assuming an appropriate loudspeaker array).

It was developed in the 1970s chiefly by Michael Gerzon. He was unhappy with the results of conventional quadrophonic sound systems which were popular at the time, especially with their tendency to “suck” the sound into the loudspeakers. Ambisonics, as proposed by Gerzon, allows homogeneous playback at any position around the listener. In more recent years it has been expanded to Higher Order Ambisonics (HOA), with a lot of work being done by Jérôme Daniel. HOA allows a larger listener area but also needs more loudspeakers.

That’s a very, very short explanation of Ambisonics that does not do this elegant system justice but there’s just too much to go into. As long as you take away the fact that Ambisonics is a cool system that allows you to place sounds around you in space then that’s maybe enough. If you want to know more then leave me a comment and I can do a much longer post that goes into some of the detail and mathematics behind it.

The reason why I want to use Ambisonics is quite simple: I think it’s a great system and I want to have some fun with it. In my work in SARC over the last couple of years I’ve used Ambisonics more than anything else and even written a paper about it. However, almost everything I’ve done has been technical. I don’t really get the chance to just bunker down in the studio and make some noise. This project will hopefully give me an excuse to do that and will have the added benefit of giving me some experience with the creative side of spatial audio and let me see its strengths and weaknesses.

Last year I designed a set of VST plugins that I hope to use in my project. I’m in the process of adding distance compensation filters (to move the sound closer or further from the listener) so when I get that done they should be good to go and I’ll hopefully make them available.

Further reading on Ambisonics:

http://en.wikipedia.org/wiki/Ambisonics – A decent place to start on the basics. I’d not stop here though.

http://www.york.ac.uk/inst/mustech/3d_audio/ambis2.htm – York University has done a lot of Ambisonics work.

http://gyronymo.free.fr/ – Jérôme Daniel’s website with some really good information and his PhD thesis (in French).

http://www.ambisonic.net/ – A good resource for some reading around the topic.

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