Abstract
This thesis examines the generation of musical sounds in brass wind-instruments. The acoustic behaviour of the instrument is first studied using the trombone and trumpet as examples. The acoustic input impedance and pressure transfer function are measured using a computer controlled, stepped sine wave technique, and these parameters are related to sound propagation in the instrument. Special attention is given to the effect of the mouthpiece. The relationship between the two measured parameters is discussed, which suggests a method of predicting some of the features of the pressure transfer function from the input impedance and an assumed radiation impedance at the bell. The input and transfer responses of an instrument to an impulse of velocity or pressure in the mouthpiece are derived from the frequency - domain data and these results correlated with the instrument's geometry. After discussion of the parameters of the instrument and player which are of importance in their interaction, particularly the behaviour of the lips when forced by the mouthpiece pressure, the literature on regeneration in wind-instruments and the speech source is reviewed. This leads to the development of a theory predicting the conditions under which a blown note will be sustained, and the harmonic structure of such a note. The theory is tested by measuring the intonation and internal pressure waveforms for a wide variety of notes blown on the trombone. The internal impedance of the pressure source from the lungs is deduced from measurements of alternating pressures in the mouth and mouthpiece and shown to have important consequences. A separate experiment investigates some of the parameters of the lip dynamics by simultaneous measurement of the pressure and velocity in the throat of a mouthpiece while various notes are being played.