Study of evaluating and measuring method of impact sound.

冲击声是以峰值高、持续时间短为特征的声音。因此，用常规方法评价和测量碰撞声的响度和噪声是不合适的。我们与日本的10个实验室合作，研究了如何通过合作研究助学金对撞击声进行评估。作为第一阶段，所有参与者在非常相似的听力条件下进行相同的实验，进行循环法测试。在这项测试中，我们使用了由微型计算机产生的反复撞击声音。用PCM将计算机合成的刺激记录在磁带上。然后，这些磁带被分发给研究人员。这次循环测试变成了一个非常大的实验，受试者的数量超过了100人。实验结果表明：(1)如果用未加权的声暴露水平来表示多次撞击声，撞击声的响度表现出较高的相关系数(0.97)。然而，为了更准确地评估响度，我们必须考虑一些时间常数来代表我们的听力系统的整体特性。(2)噪声评估实验的结果表明，未加权的声压级显示出很高的相关系数(0.99)。这意味着，该测量方法对于评价反复撞击声的噪声是相当有效的。

Impact sounds are such sound that are characterized by their high peak levels and short duration time. Thus, it is not appropriate to evaluate and to measure the loudness and the noisiness of impact sounds by conventional methods. We have studied how to evaluate the impact sounds in cooperation with ten laboratories in Japan by Grant-in-aid for Co-operative Research. As the first stage, a round robin test, in which all the participants conduct the same experiments under very similar listening condition, was carried out. In this test, we used repeated impact sounds which are generated by a mini-computer. The stimuli synthesized by a computer were recorded on magnetic tapes by using PCM. Then the tapes were distributed among researchers. This round robin test becomes a very large experiment where the number of the subjects were more than a hundred. The experimental results obtained by the test were as follows:(1) If we express a repeated impact sound in terms of the unweighted sound exposure level, the loudness of the impact sound show rather high relation coefficient(0.97). However, to evaluate the loudness more precisely, we have to consider some time constant which is consider to represent the integral characteristic of our hearing system.(2) As a result of the experiment for noisiness evaluation, the unweighted sound pressure level showed a very high relation coefficient(0.99). This means that this measure is quite effective to evaluate the noisiness of the repeated impact sounds.