Brass wind instrument impulse response measurements
A. H. Benade, Jeffrey H. Smith · The Journal of the Acoustical Society of America · 1981
Apparatus has been built for pulse reflectometry of brass instruments. The current version uses spark excitation and an electret microphone at the mouthpiece rim terminating plane. Selectable low pass filtering in the microphone channel reduces noise and aids in the visual interpretation of reflected pulses via control of signal bandwidth. Discontinuities of air column cross section, taper, etc. can be located and identified using familiar techniques from electrical reflectometry. Multiple-reflection patterns characteristic of prototype musical shapes must be taken into account. These are being worked out. Reflectogram FFT's give input impedance functions in good agreement with those obtained via swept frequency capillary excitation methods. Studies of several tubas show that availability of both time and frequency domain representations of the response function greatly increases diagnostic power for the evaluation and correction of instruments. Comparisons will be made with reflectometer data of Krüger (Zwota, DDR) and the tuba impedance measurements of Caussé (IRCAM, Paris). [Work supported by NSF.]