The effect of wall materials on the timbre of brass instruments

Abstract

It has long been thought by players and instrument makers that the material from which a brass instrument is made influences the tone quality and playing characteristics of the instrument. For instance, the brochure of a maker of custom trombones describes bells made of three alloys: yellow brass (70% Cu, 30% Zn), having the ‘‘clearest sound, sharpest articulation,’’ gold brass (85% Cu, 15% Zn), with ‘‘warm sound, rounded articulation,’’ and red brass (90% Cu, 10% Zn), with ‘‘warmer sound, covered articulation.’’ The bells are made in three metal thicknesses: light weight, with ‘‘flexible tone, rapid response,’’ standard weight, with ‘‘balanced tone, even response,’’ and heavy weight, with ‘‘firm tone, stable response.’’ Most players agree with these statements. This model of trombone is made so that bell sections can be interchanged while leaving the remainder of the instrument intact. The present paper reports the results of measurements under playing conditions on several different bells. Comparisons of steady-state behavior are made via the transfer function between sound pressure in the mouthpiece cup and an on-axis point outside the bell. An attempt will also be made at the rather more difficult task of characterizing the attack transient.