An acoustic impedance probe for the teaching of musical acoustics to non-majors

Abstract

Physics of Music or similar titles are found in the course catalogues of many colleges and universities. Almost always such courses are directed at non-physics majors and even non-science majors. As a result the course materials must be presented without reliance on advanced mathematical concepts, and thus a great deal of in-class demonstrations combined with video clips are used instead. For example, the concept of acoustic impedance, when introduced rigorously, requires the use of complex algebra. However, a discussion on a qualitative level can be done in a way that is accessible to undergraduate students without a great deal of math background. In order to introduce some measure of quantitative discussion, we are using a simple home-built impedance probe to record the input impedances of simple air columns as well as real instruments. In this talk we will discuss the details of the impedance transducer and show how it can be used to demonstrate how a flared bell changes the resonances of cylindrical air columns, the effect of differently shaped mouth pieces on the acoustic properties of a brass instrument, and a number of other characteristics of musical instruments.