An innovative design of a probe-tube attachment for a 1/2 -in. microphone

Nonintrusive devices are needed to measure sound pressure levels in the mid- to high-frequency range. This need arises due to the small acoustic wavelengths which are present at these frequencies, and the interference caused by conventional microphones which are typically of relatively large diameter. Smaller microphones are less sensitive, and may not be small enough to be useful at very high frequencies or when physical size constraints are limiting. Simple probe attachments have been developed by others to address these problems; however, generally the transfer functions of these devices have possessed undesirable peaks due to the presence of standing waves within the transducers. In this paper, several possible options for making a microphone attachment that will convert a standard 1/2 -in.-diam microphone into a probe-tube are discussed. Recommendations are made with regard to the particular use and ease of construction of the attachment. The new concepts eliminate standing waves, within certain frequency bands that are controlled by the geometry of the attachment, without the addition of damping material in the sound path.

Duke Scholars

Author Linda Franzoni Thomas Lord Department of Mechanical Engineering and Materia ...