Voice communication and positive pressure breathing in noise

The speech intelligibility of talkers and listeners using military voice communications equipment was measured in the laboratory under conditions of positive pressure breathing and tactical aircraft cockpit noise environments. Results indicated that positive pressure breathing did not significantly degrade speech intelligibility until the noise environment reached 115 dB. A trend suggesting that intelligibility decreased with increased pressure was observed across the other experimental conditions. Positive pressure breathing did contribute to changes in speech production which resulted in increased talker effort and decreased speech quality. A new respiration valve that could operate at lower mask pressures and would have lower internal noise levels might be highly desirable for aircrews. Speech intelligibility changes due to the cockpit noise conditions were typical of those seen in previous experiments where the percent correct responses decreased with increased levels of the noise.