Page  118 ï~~Ambisonics Technique for Low Dimensional Sound D.G. Malham Music Technology Group University of York Heslington York YO1 5DD Email: dgm2( ABSTRACT: Ambisonic systems store in soundfields that can be used to produce vta a illusion of true three dimensional sound image theory that reproduce the soundfield prese channels are needed. Ambisonics is based on stc be available from a simple combination of micro using that information to fool the ear into perce the system means that complex mani; accomplished using computers. In the lath 1 O)tn" n'n A n,-pl 101 ' Qnl' farmflI Fce n I I c S F

Page  119 ï~~Having the i1 accomplished. nformation recorded in this form, the 1 This is completely separate from the place and is based on an amalgam of various theories and high frequency mechanisms. Amnbtsonic decoder Further details are in the full paper, which is available The question must be posed "How does this approach quadraphonic approach was based on a very simple t as one hole in a concert hall wall, stereo systems as mono, it was assumed that four holes would be bett extra information carried is redundant, which causes perceived images, particularly along the sides. Extensive listening tests over many years show other form of recording at reproducing sound mage unde applications in electro-acoustic music? To theory on Ambisonics. BASICAMBISONIC TECHNOLOGY The Ambisonic surround sound system essential w M.W M wm = W. I

Page  120 ï~~Further modifications can be made to allow for an ov posit ion, which may be more natural. Moreover. as well soundffieldq the whole soundfield can be modified as in tl To rotate a complete soundlfieid., Vw pitL' any nurn by an arbitrary angle a an~d tilt it about the v axis b, transform to the B Format signals representing the sounc -X.cosa.costb Y.sina.cost6 + Z.sintb V.O~ - X.Sll? = Z.cosb - X.cosa.sin b + Y.sina.sinb W' Many other effects are available. such as mtrror imaginj etc. These may all be contained within one miatrix thus. x" w" = k1.X + k2.W + k3.Y 0- k5.X + k6.\V + k7.Y +k4.Z + k8.Z = k9.X = k13.X +klO.W +kll.Y +k14.W +klS5.Y.+-k12 + k16.Z where k 1. k 1.6 are coefficients formed by the matricf 'E appear in all the different modification equations \which Other possibilities which open up once xve move to f 0 anifltc of rv rh~rt nrlnd flnanin +nht, nnart inn