While commonly used ground impedance deduction methods often utilize pairs of vertically separated microphones, deployed arrays rarely have this configuration, which increases the difficulty in automatically deducing local ground impedance from these arrays. The ability to deduce ground impedance using random sounds incident on a three-dimensional array would increase, for example, the accuracy of estimated elevation angles. The methods described by the American National Standards Institute Method for Determining the Acoustic Impedance of Ground Surfaces are extended to simulate deducing ground impedance by a three-dimensional array. Ground parameters indicative of grassland are successfully determined using a simulated three-dimensional array.