About This Reverberation Business

When music is performed in a concert hall, a torrent of echos from the various different surfaces in the room strikes the ear, producing the impression of space to the listener. This effect can vary in evoked subjective response from great annoyance or even incomprehensibility, in the case of speech presented in a highly reverberant auditorium, to sheer ecstasy, in the case of late romantic music in the Vienna Grosser Musikvereinsaal. Most music is heard these days either in the comfort of one's home (or car), or in a university auditorium, both of which have generally short reverberation times. For this reason, most recordings of music already have some amount of reverberation added before distribution either by a natural process (i.e. recordings made in concert halls) or by artificial processes (plate or spring reverberators). Computer music is an especially fertile ground for artificial reverberation in that it is rarely, if ever, performed in highly reverberant concert halls. The use of the computer for the simulation of this reverberation also allows the composer another degree of freedom, namely to tailor the reverberation to the particular aural effect he wishes to present, allowing, for instance, each individual sound in the piece to carry an entirely different spatial aspect, if desired. In this paper, we review some of the work that has been done in the production of artificial reverberation by computer, and we present the fruits of our own labors along this line, both in the attempted simulation of the concert hall environment by computer and in the proliferation of different circuits for the realization of simulated room reverberation.