Abstract
The “synchronized correlation method” is a new correlation method which is useful for the field measurements of short-range sound propagation over a ground surface and for the impedance measurements of the surface. The advantage of the new method is that the coherency between transmitted and received signals can be recovered with the aid of a pilot signal and the measured cross-correlation function represents the impulse response of the acoustic system under test. Experiments are made over a turf-covered ground in two varieties of source-receiver arrangements. From the results in the vertical arrangement, the acoustic impedance of the ground surface is estimated. Experimental results in the horizontal arrangement are found to be in good agreement with the theoretical ones calculated from the estimated impedance. The effect of the irregularity of the ground surface is discussed.
