from quadro to surround-sound

1n previous articles (`Quadrille` and `music of the spheres`, Elektor 17, September 1976, p. 910) it was noted that `Amb ison ics` was erhaps the most promising of the quadrophonic systems proposed so far. This led to a reaction from Prof. P. Fellgett, pointing out (amongst other things) that he preferred to use the phrase `surround sound` since `quadrophonics` rather over-stresses the number four - quite apart from being a condemnable mixture of classic tongues. Since we had very little information on Ambisonics at our disposal, we took the opportunity to ask him to write a short article explaining the basic theory and philosophy of Ambisonics. His text reached us only three weeks later (I), and it is presented here in full. Where some further comments or explanation seemed necessary, we have given this separately 1 as an `editorial note`. But first let us see what Prof. Fellgett has to say.