Speed of Sound in Gases Measured by in Situ Generated White Noise

摘要

The speed of sound in gases is measured by in situ generated white noise in an acoustic tube. The white noise is generated by the expansion of compressed gas rather than electronically. An acoustic tube acts as a resonant filter. A Fourier transform of the recorded sound pressure can identify the resonant acoustic modes which can be related back to the speed of sound in the gas. The student results with this method were compared to prior student results which measured the wavelength of single frequencies by phase comparison. The Fourier transform method using in situ generated white noise showed better accuracy.