RECIPROCITY CALIBRATION OF IMPULSE RESPONSES OF ACOUSTIC-EMISSION TRANSDUCERS

By means of reciprocity calibration in Rayleigh-wave and longitudinal- wave sound fields, frequency characteristics of amplitude and phase of absolute sensitivity of acoustic emission transducers were measured o n the basis of the newly derived complex reciprocity parameters, and t he impulse responses were obtained through inverse Fourier transform. Calibration results were confirmed with supplemental experiments in wh ich the fracturing of a pencil lead was utilized for the source of ela stic waves. Impulse responses of acoustic emission transducers to both the Rayleigh-wave and longitudinal-wave displacement velocities were determined by means of purely electrical measurements without the use of mechanical sound sources or reference transducers.