Effect of microphone type and placement on voice perturbation measurements

This study was conducted to explore the effects of microphone type (dynamic vs. condenser) and pattern (omnidirectional vs. cardioid) on the extraction of voice perturbation measures for sustained phonation. Also of interest were the effects of distance and angle between the source and the microphone. Four professional-grade and two consumer-grade microphones were selected for analysis. Synthesized phonation with different amplitude and frequency modulations at fundamental frequencies of 100 Hz and 300 Hz were presented over a loudspeaker. Human phonation was also included to test the validity of loudspeaker presentations. Three microphone distances (4 cm, 30 cm, 1 m) and three angles (0 degree, 45 degrees, 90 degrees) were used for microphone placement. Among the professional grade microphones, the cardioid condenser type had the smallest effect on perturbation measures. In general, condenser types gave better results than dynamic types. Microphones with an unbalanced output did not perform as well as those with balanced outputs. Microphone sensitivity and distance had the largest effect on perturbation measures, making it difficult to resolve normal vocal jitter at anything but a few centimeters from the mouth. Angle had little effect for short distances, but a greater effect for longer distances. These conclusions are preliminary because the sampling of microphones, distances, and signal types was very coarse. The study serves only to chart the course for future work.