Impulse measurements on tubular acoustic systems.

This thesis investigates the transient measurement and analysis of brass musical instruments. The experimental apparatus of Deane (1986) has been substantially revised and developed to allow accurate determination of the input impulse response of instruments up to 8kHz. The inverse problem of calculating the bore of an instrument from its impulse response has been studied with good success. The bores of trumpets have been accurately determined to within 0.1mm up to the bell section where the flare is too great for the algorithm to be valid. Further developments have been made to the application of transient measurements to the manufacturing environment. The apparatus has been shown to detect valve misalignments as small as 0.25mm. A modified apparatus has been developed to allow determination of the input impedance of instruments from transient measurements. The shape of the calculated impedance curves show good agreement with measurements made in the frequency domain although absolute calibration shows errors related to truncation of the transient responses. The internal field of a French Horn bell is studied with the results presented in a series of space-time and space-frequency diagrams. This technique allows detailed examination of the shape of an impulse travelling through the horn. Finally, the relationships between impedance, impulse response and bore have been analysed to form the foundations of a Computer Aided Design technique for brass instruments