Page  60 ï~~DISORDER SOUNDS Theory and Practice in Instr M M P.J. Comerford and L.I Iicrocomputer Music R Department of Con University of Bra( Bradford, West Yo England BD7 1 peter@ bradford.c ABSTRACT: The role disorder as C investigated, and its importance is evaluate types of disorder in musical sound, including random changes in amplitude and freque decay of upon the ensemble of disord partials, and t perception of n v. are discussed. 1 " Tl uning disorder. T nusical instrument The paper includ he sc eVs r -- ler for simulation, and some sync u -.Sr - authors are described.

Page  61 ï~~while the fundamental takes maximum amplitude. This oi 86ms rder of - much longer th differential develh member, and mu stops of produce long as treatment which the gemshom is a a perceptually acceptable the attack characteristics t can be applied to the L 1 exampl of the attack of a a tor most proi disorder c musically unacceptable detriment to the sound. Differences in partials' amplitude I timbres but across the temporal differentials experimentally. pitch range contributes onset rates of individual to the perc orga:eptio and 1 tU Wild fluctuations frequency Can occur during established. frequency t arresting pe The tXr iehaviour e;rceptmal e. iling of the ffects nature perceived of c reed/pipe combination can be created by star )rg d rd, - d1 t that they clash against each other during attack and b note. An approximation to the bow-scrape effect on by wildly varying frequencies during the attack perio T, a~t~ an a--a-4- ay ~ Atff1AA11 n.. ".A 0 I

Page  62 ï~~d.tuning disorder Polyphonic insi which becomes truments a are in practice seldom precis when chords rather than sing imprecise whe inevitable sm, significant coreoigds timbre is also "softer" by an hInf r a] apparent many act l deviatio )ustic instruments or - - XIS between unisons mI ntribution the perception of ei from a simulation. iany o1 and o mnsemb..Thee )rdered tuning I of'itrs an organ reed chorus car increase in the de-tuning within and bet Effects of acoustic upon the perception of disorder I~n a reverberant acoustic, the listener hears not just U, sound bouncinj sound, and alter length of time there is a clash sustain period c concurrent coat chest fvwnnenrv ri (o back from many points 2g its timbral balance an )r wbich the disordered )f frequencies at the star.L Li in mhe Duil( d1 lengthenin; attack transit t of a note, I )f th( Elict.4 e, note so that th A related effect Affect (*-I where eu sounds are hear as ceen encounUc 2 deadi 2Cflhl snag lea! ci, c