The measurement of acoustic non-linearity parameter B/A in ethanol and milk

摘要

A finite amplitude insert-substitution method for the acoustic non-linearity parameter B/A of two liquid samples of ethanol and milk is performed using a transmitter/receiver pair. Firstly, a model of the non-linearity parameter B/A is presented, which combines attenuation with diffraction correction. Next, the B/A values of the ethanol sample are estimated at different temperatures, different sound intensities and different frequencies by using a band-pass filter to extract the second harmonic signal. Finally, the B/A values of the milk sample are measured to detect the deterioration process of the milk with time. Experimental results show that the measured B/A values have an approximately linear relationship with temperature and frequency, respectively, and the B/A values are independent of the sound intensity. Furthermore, the measured B/A values of the milk distinctly change with time during the sixteen hours' storage time.