Passive acoustic thermometry

Elliott, AS

Abstract

Conventional acoustic thermometry is usually performed by exciting a resonator with a sound source and identifying the resonant frequencies of the system. If the dimensions of such system are known it is relatively straightforward then to determine the speed of sound and from that the temperature. Alternatively a sound source and receiver separated by a short distance can be used to determine the speed of sound, and hence temperature, by measuring the time delay between source and receiver but neither approach is widely used in practise. Described in this paper is an alternative approach to acoustic thermometry which we refer to as “Passive Acoustic Thermometry” (PAT) because it does not require a dedicated sound source. Instead, background or ambient noise is used to excite a resonator containing a microphone and an additional microphone outside the resonator replaces the sound source. It is demonstrated in the paper how the frequency response function between the two microphones can be used to determine the resonant frequencies of the system and how this data can be used to determine air temperature. In principal the same device could also be used to measure relative humidity and this, together with some potential applications is discussed.

• Presentation Conference Type: Other
• Conference Name: Internoise 2016
• Publication Date: Aug 22, 2016
• Deposit Date: Sep 1, 2016
• Publicly Available Date: Sep 1, 2016
• Publisher URL: http://www.internoise2016.org/
• Additional Information: Event Type : Conference