Detection of sound radiated from a specific device using hand-held sensor probe for surface intensity measurements - Precision of measurements in noisy environments

摘要

Surface acoustic intensity, which is a vector quantity defined as an energy flow of sound per unit area, is a useful measure for the identification of structure-borne sound that is radiated from a specific surface of a machine or a device in operation. In this technique, the intensity is determined by the sound pressure and the normal velocity on the vibrating surface, which are directly measured by a microphone and a vibration pickup, respectively. In order to facilitate multiple point measurements, an efficient technique for setting two different sensors is required. One idea is to combine the microphone and the pickup in a single sensor device. In this paper, a hand-held sensor probe is proposed and the application is described. The sensor probe is composed of a 1/2-inch condenser microphone and a vibration pickup of 1 g (= 10~(-3) kg). The two components are connected with a damper made of silicon rubber that isolates the transmission of the vibration. The precision of measurements is confirmed by the experiments in noisy environment. The sensor probe is applied to the detection of sound radiated from a hard disc drive unit working as a PC peripheral device in an office setting.