ELECTRO-PNEUMATIC LOUDSPEAKER AND THE SPEECH INTELLIGIBILITY IN LONG RANGE BROADCASTING

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 soundsource it can be used as a broadcasting sound source to reproduce speech and music.The acousticpower output of the sound source developed is 2000W;the power output at l000Hz deviates less than4 dB from the highest power output in its frequency range.The intelligibility of sentences recordedword for word at 5.8 km distance from the single sound source is 56%.And for an array of foursources,the intelligibility of sentences recorded word for word is 58% at 8.7 km from the soundsource,and 32% at l0.2 km from the sound source.The subjective rating for short passages isnearly intelligible at 8.7 km from the sound source,and less intelligible at 10.2 km from the soundsource.The experimental results show that the obtained intelligibility is dependent on the educa-tional level and the sense of responsibility of the list     

测量用驻极体电容传声器

本文介绍了用于精密声学测量的驻极体电容传声器的结构、设计原理及主要性能。该种传声器的主要特点是采用金属振膜后驻极体结构,因而它既具有电容传声器的灵敏度高,频响平直、动态范围大及稳定性好等优异特性,又兼不需要外加极化电压及可在高潮湿环境下工作的特点。因此特别适宜于与微机配套而形成完整声信号提取和处理装置。在当前的声学研究及环境噪声监测等领域具有广泛应用价值。     

调制气流声源和远程广播中语言可懂度的实验研究

调制气流声源已广泛地用来作为模拟强噪声的声源。本文的研究工作表明,适当展宽高频响应,它能作为重播语言的广播用声源。我们研制的声源;输出声功率2kw,1000Hz处输出功率不低于最大值4dB,用它来广播语言,在5.8km处,逐字记录短句的可懂度是56％。四个声源组合,在8.7km处是58％,10.2km处是32％;短文可懂度的主观评价,在8.7km处是基本听懂,10.2km处是比基本听懂差,比听懂一半又要强。由于逐字记录的条件较严,因此与测听人员的素质,主要是文化程度和责任心有关,实验表明具有高中文化程度的比初中的平均逐字记录短句的可懂度要高10％。实验值是在一般气象条件下,在室外自然环境中,多次测量的平均值,测听人员未经任何训练,所以,结论具有一定的实用价值。