Standardization of equal -loudness level characteristics

听力实验是在一个大的消声室中进行的，以获得等响度水平等高线。在实验中，测量了纯音在20、40和70个声道时的等响度能级轮廓以及自由场中纯音的听阈。通过实验得到以下结果：(1)在低于1 kHz的频率范围内，所有被测电平的等响度等值线与现行的国际标准ISO 226的误差都在10dB以上。这意味着现行标准应该进行彻底的修订。(2)所有的听阈数据都提交给了TSO(国际标准化组织)TC43。决定与德国和丹麦的其他数据和其他数据一起发布新的国际标准ISO 226第1部分。我们对这一标准化做出了重大贡献，因为只有我们组才能提供覆盖整个可听频率范围的数据。(3)我们发现，在等响度等高线和听力阈值之间，都存在一个约2分贝的小峰值。将这一峰值与单个头部传递函数(从声源到听者外耳的声学路径的传递函数)进行比较，我们发现该峰值可以通过头部传递函数中的相应凹陷来解释。这说明头部传递函数是决定个体等响度轮廓和听力阈值的重要因素。

Hearing experiments to derive equal-loudness level contours were carried out in a large anechoic room. In the experiments, the equal-loudness level contours of pure tones at 20 phon, 40 phon and 70 phon as well as the threshold of hearing of pure tones in a free field were measured. We get the following results with the experiments.(1) The equal-loudness level contours at all the levels examined show discrepancy from the present international standard, ISO 226, by more than 10 dB in lower frequency range than 1 kHz. This means that the -present standard should be totally revised.(2) All the data of the threshold of hearing obtained were presented to TC43 of TSO (International Standardization Organization). It is decided that a new international standard ISO 226 Part 1 is to be published with other data and other data from Germany and Denmark. We contribute this standardization remarkably because only our group could present such data that covered all over the audible frequency range.(3) We found that a small peak of around 2 dB exists between 1 kHz and 2 kHz for both the equal-loudness contours and the threshold of hearing. Comparing this peak with individual head transfer functions (transfer function of a acoustic path from a sound source to the listener's external ear), we found that the peak can be explained by a corresponding dip in the head transfer functions. This shows that the head transfer functions is an important factor to determine individual equal-loudness contours and threshold of hearing.