Manufacturing of Metallic Tubes for Wind Musical Instruments

Abstract

Wind musical instruments are aerophone, producing sound through the vibration of an air column. A simplified model of a wind instrument includes the source of air, the sound generator, the resonating air column and the radiation of sound. If we make reference to how air column is excited by means of vibrating reed, the following classification of wind instruments can be proposed: mechanical reed instruments, lip valve instruments and air jet instruments. For clarinet, oboe, bassoon, saxophone—the playing pitch is based on the first two modes of the resonating air column. The length of the air column of these instruments is adjusted by tone-holes that are opened or closed in various combinations to play a required musical note. The geometry of lip driven instruments (horn, trombone, trumpet, etc.) is rather simpler than that of air jet or mechanical reed instruments (clarinets, oboes, etc.). At the same time lip driven instruments are more difficult to manufacture. The resonance peaks observed on an impedance graph are located at the harmonics of the vibrating air column of a specific length. The alignment of input impedance peaks is a very important property of a brass instrument for its acoustic response and for accurately playing different notes in tune. Acoustical behaviour of wind instruments can be studied through their acoustic impedance spectrum, measured at embouchure or “input” to the instrument. the acoustic impedance is defined as the ratio of acoustic pressure to acoustic volume flow. Commonly the input impedance variation is represented versus frequency, illustrating the linear acoustic response to a sinusoidal input signal.