Methods for Measuring the Acoustic Properties of Wind Instruments

Abstract

The sound field is determined by the sound pressure and velocity, which characterize its temporal and spatial properties. The speed of sound in air depends on temperature but is independent of frequency. Sound wave length is dependent on frequency. Under ambient conditions, radiation properties of wind instruments expressed by transfer function between internal acoustic pressure (inside the tube of the instrument) and the radiated field are related to the tonal quality of those instruments. Acoustic pulse reflectometry is an appropriate tool for the detection of air leaks in wind instruments. During the past decades nondestructive optical techniques have been developed for detection of vibrations of wind instruments. Optical techniques emerged as dominant technique over traditional techniques for detection of vibrations of wind musical instruments, because of their real time character. Laser Doppler vibrometry and holographic interferometry are described. These methods have the sensitivity and a very good spatial resolution to visualize the sound field in wind musical instruments.