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Ambisonic systems are frequently employed in acoustics research facilities in Universities. In the UK there is one at Derby University as part of the Signals Processing Faculty under Peter Lennox. at York University there is an Ambisonic system maintained by Dave Malham. Angelo Farina has a system at the University of Milan, Italy. The world authorities in this area can be found on the majordomo sursound discussion forum. Of course I have no information about private systems, but people in the UK who would like to hear an Ambisonic system may wish to contact the appropriate academic facilities at the respective Universities and perhaps they can arrange a visit. There may be a charge. Ambisonics never took off because of lack of investment and the commercial stronghold of 5.1 film surround sound in the early days. Ambisonics is still an excellent system, and if truly coherent periphonic surround sound is required, definitely the way to go despite its limitations. Interestingly it is possible to recode B Format Ambisonic sources to 5.1, and an example of this can be found as a 5.1 DTS track on a Rick Wakeman album I was involved in recording a few years ago at Lincoln Cathedral, available on the Voiceprint website. Try sitting a little foward of the central position for the best surround perception on this track. There are a series of Lincoln recordings featuring The Ric Sanders Group, Howard Riley and Roger Eno, each album contains headphone binaural and 5.1 DTS (Ambisonic) surround sound and although the recordings are somewhat experimental and variable in quality, some appreciation of both headphone binaural surround and planar Ambisonics (without height) can be appreciated from these recordings. Also bear in mind that these are pure microphone recordings on location, not studio multimixes. A brief extract of some of the headphone binaural tracks above can be found on my website: Dallas Simpson's Homepage dallas.

Surround - headphone / speakers I'd just like to add some comments to the 5.1 / binaural / surround sound debate on a previous set of mails. There are some complex and subtle issues being raised here. First speaker surround sound. The most sophisticated approach at present is Ambisonics a multichannel speaker system capable of handling up to 32 speaker channels in a number of speaker configurations, but most important the system includes height information. The technology is established, but very high end audio Meridian make decoders. Audio is usually presented in B-Format, 4 channels of specially matrixed audio containing the x,y,z co-ordinate pressure and velocity components of three dimensional sound plus a mono component. In B-Format these are designated W,X,Y,Z, where W is the mono component. There are levels of sophistication described as orders, 1st Order Ambisonics utilises four algorithms to extract the surround information from B-Format, 2nd Order uses nine, and a lot more processing! The aim of true speaker surround is to try and reconstruct the true surround waveform sampled at a point by a suitable microphone or microphone array. There is no true point microphone at present able to do this perfectly. Soundfield make a mic that is very good and there is the very expensive holophone. 5.1Surround was never intended for true surround sound with height. It evolved from the film / video industry and provided a satisfactory means of delivering a good stereo front image, with central dialogue, and surround fill to the rear. Great for wizz-bang effects if only a crude horizontal planar surround sound field is required. Modern state of the art surround mixing is gradually embracing Gerzon's work. Interestingly Ambisonic material can be re-coded for 5.1 to give a convincing, if rather broad brush stroke, planar surround sound through speakers. True surround requires integration of all speaker feeds amplitude panning between speakers will not do and this is where the Ambisonic approach, deriving largely from the work of Michael Gerzon, wins through. Headphone surround - binaural is the primary technique, but headphone surround is a totally different experience and challenge for music and sound art production. I hope to continue this later, meanwhile I have to set up for a performance in Nottingham today. Speak soon, Dallas Simpson.