Timbre of marching-band brass instruments

The tone quality of brass instruments for outdoor use has varied from time to time and from place to place. Instruments currently in use can be recorded and analyzed. However, many older instruments, typically those in museum collections, are not allowed to be played. Hence, it is necessary to rely on measurements of physical dimensions and acoustic input impedance to form comparisons. In this paper, such measurements are used to estimate two important timbral parameters: the spectral centroid at moderate playing levels and the brassiness potential. For different instruments of the same pitch, like trumpet and flugelhorn, the spectral centroid gives a measure of the brightness or darkness of the tone. The brassiness potential gives a measure of the degree to which the tone develops a “brassy” edge at high playing levels. As one might expect, the trumpet has both a higher spectral centroid and a higher brassiness potential than the flugelhorn. Results will be shown comparing instruments built in different countries and at different times.