Air Flow and Sound Generation in Musical Wind Instruments

Abstract

Over the past two decades or so, interest in musical acoustics appears to have been increasing rapidly. We now have available several collections of reprinted technical articles (Hutchins 1975, 1976, Kent 1977), together with a large number of textbooks, of which those most suitable for citation in this review are by Olson (1967), Backus (1969), Nederveen (1969), and Benade (1976). The mathematical foundations of the subject were laid primarily by Lord Rayleigh (1896) and are well treated in such standard texts as Morse (1948) and Morse & Ingard (1968). This review covers a much more restricted field than this preliminary bibliography might suggest. Among all the varieties of musical instruments I concentrate on those capable of producing a steady sound that is maintained by a flow of air, and even within this family I am interested not so much in the design and behavior of the instrument as a whole but rather in the details of the air flow that are responsible for the actual tone production. Although musical instruments function as closely integrated systems, it is convenient and indeed almost essential for their analysis to consider them in terms of at least two interacting subsystems, as shown in Figure 1. The first of these is the primary resonant system, which consists of a column of air, confined by rigid walls of more or less complex shape and having one or more openings. Such a system is generally not far from linear in its behavior and it can be treated, at least in principle, by the classical methods of acoustics. The second subsystem is the airdriven generator that excites the primary resonator. This subsystem is generally