It’s all in the bore!

Abstract

A review of the current state of knowledge concerning the influence of wall vibrations on the sound of brass wind instruments, flue pipes, and woodwind instruments is given. The question of whether this influence is strong enough to be objectively observable is still a controversial issue. While instrument makers and musicians make a strong claim that wall thickness, material, and conditioning are crucial factors for sound quality and response of wind instruments, acousticians tended—at least in the past—to attribute all acoustical characteristics to the actual bore profile. Recently this seems to be changing. First, there is growing experimental evidence favoring the hypothesis that wall vibrations do matter; second, theoretical models are starting to be developed which deal with the interaction between the air column sound field and its oscillating boundary conditions. Another suggested theory is that wall vibrations are propagated back to the mouthpiece interacting with the player’s lips affecting the delicate and strongly nonlinear mechanism of sound generation. Even the question of whether vibrating bells can radiate a significant amount of sound does not seem to have reached a final answer. New experiments have been conducted to help answer these open questions. a)R. A. Smith, ‘‘It’s all in the bore!,’’ International Trumpet Guild Journal, 12(4) (1988).