ELECTRO-PNEUMATIC LOUDSPEAKER AND THE SPEECH INTELLIGIBILITY IN LONG RANGE BROADCASTING
Kevin Hang · 声学学报(英文版) · 1983
The electro-pneumatic loudspeaker has been used widely as a sound source of high intensity noise. Investigation in this paper shows that by suitably increasing the upper limit frequency of the sound source it can be used as a broadcasting sound source to reproduce speech and music. The acoustic power output of the sound source developed is 2000 W; the power output at 1000Hz deviates less than 4 dB from the highest power output in its frequency range. The intelligibility of sentences recorded word for word at 5.8 km distance from the single sound source is 56%. And for an array of four sources, the intelligibility of sentences recorded word for word is 58% at 8.7km from the sound source, and 32% at 10.2 km from the sound source. The subjective rating for short passages is nearly intelligible at 8.7 km from the sound source, and less intelligible at 10.2 km from the sound source. The experimental results show that the obtained intelligibility is dependent on the educational level and the sense of responsibility of the listeners. Since the experimental conditions are similar to practical conditions (average weather conditions, listening in the field, and untrained listeners), the conclusions obtained have some practical value.