Wind instrument bores in the time domain
R. Dean Ayers · The Journal of the Acoustical Society of America · 1988
Recent interest in modeling nonlinear feedback control of the driver has led several researchers to examine Green's functions and reflection impulses for wind instrument bores. These are usually obtained as inverse Fourier transforms of experimental or computational results in the frequency domain. At CSULB, the focus instead has been on developing such waveforms stepwise, using multiple convolutions. This was motivated by the desire to obtain a better intuitive understanding than that provided by just the transmission line model in the frequency domain. Central to this work are such basic concepts as causality and round trip delay time. The intuitive power of this theoretical approach correlates nicely with the cleanness of experimental results obtained directly in the time domain, which allow us to isolate the effects of individual bore elements. The experimental technique employs Wiener filtering to generate a brief acoustic pulse from a piezoelectric element. Resultant waveforms are further processed by a Scientific Atlanta SD-380 spectrum analyzer, with data sent backward through an IBM-PC to average out low-frequency noise. [Work supported by the CSULB Foundation.]