This study presents a development on a time efficient approach to measure
the Acoustic Impedance of Industrial Insulating materials using an impedance
tube with single moveable microphone and a white noise generator. The standing
wave method is used to measure the acoustic properties (absorption coefficient and acoustic impedance) of sound absorbing materials. In order to use a
burst of white noise instead of individual stationary sine waves, a signal
processing technique was developed. The algorithm is based on the equation of
simple harmonic motion, but uses distance as a variable, instead of time. This
innovative method allows measuring at frequency resolutions as low as 5 Hz in a
reasonably short amount of time. This is an advantage,
as the classical standing wave method uses frequency resolutions of one-third
of octaves for measurements, as otherwise time would be prohibitive.
Experimental results are validated with those measured with the sine wave
generator using one-third of octave frequencies by comparing their behaviours.
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