Development of TTS meter and evaluation on the hearing-effect of environmental sounds by using it

我们开发了一个在实际噪声场中实时预测TTS（临时阈值移位）的系统。该系统由带有三分之一倍频带滤波器的声级计和一台多用途个人电脑组成。首先，考虑了一种计算程序，以实现实时操作。考虑到这一点，我们发现TTS的预测值可以表示为测试频率的临界频带频谱电平与从现有预测方程中得到的脉冲响应的卷积和。对于Takagi的预测方程，当采用稳定噪声的相同程序处理适用条件时，可以观察到预测TTS的增长有时间延迟。考虑了一种适当的方法来消除时变噪声的时间延迟。通过该系统，我们从TTS的角度评估了一些环境声音对听力的影响。

We have developed a system which predicts TTS (Temporary Threshold Shift) in real time operation at actual noise induced fields. This system consists of a combination of a sound level meter with one-third-octave band filters and a multi-purpose personal computer.At first, a calculation procedure was considered to enable real time operation. In this consideration, it was found that the predicted value of TTS can be presented as the convolutional summation of the critical band spectrum level for the test frequencies and the impulse response obtained from the existing prediction equations. For Takagi's Prediction Equation, a time delay in the growth of the predicted TTS was observed, when the applicable conditions were processed by the same procedure for steady noise. An appropriate procedure to remove the time delay for time-varying noise was also considered. By using this system, we evaluated the effects of some environmental sounds on hearing in terms of TTS.