Performance of LPC vocoders in a noisy environment

Although 2400 BPS vocoders based upon Linear Predictive Coding have produced speech intelligibility scores as high as 90% in a quiet laboratory setting, few actual system measurements have been made in noisy, stressful, military environments. This paper describes LPC vocoder performance in high acoustic noise environments and when the speaker is subjected to stress, vibrations and accelerations. Measurements were made on military platforms which included ships, conventional aircraft, helicopters, tracked vehicles and wheeled vehicles; acoustic noise levels varied from 70 to 125dB Sound Pressure Level. (1)