2003 Volume 65 Issue 6 Pages 77-84
The goal of this study is to develop a method to distinguish a speech sound source of a tractor operator using a microphone-pair. The axial distance characteristics of the microphone-pair were first measured and compared to sound theory. The microphone-pair was then used to measure an artificially produced rectangular wave in order to verify the efficiency of the ratio of pitch level between the two microphones. It was clear, consequently, that the sounds produced at the operator location were distinguishable from sounds originating outside the tractor cabin. Also, the ratio of vowel pitch level was used to detect vowels, uttered by the operator, and distinguish those from utterances outside the tractor cabin. The study concludes by introducing methods for improving the measurement techniques for the ratio of vowel pitch level and for increasing the accuracy of the operator's voice detection system.
