Abstract
The threshold of hearing for pure tone under free field listening conditions were measured to prepare basic data for a full-scale revision of the international standard ISO 226. The frequency range for the measurements was 31.5 Hz-16 kHz. Number of subjects was 16-69 depending on stimulus frequency. The following features are shown by comparing our data with others.(1) The thresholds of hearing do not have any great difference from other data, but some systematic deviations from ISO 226 are observed, i. e., our data are 2-6 dB higher at frequencies below 160 Hz and 1-3 dB lower at frequencies between 400 Hz and 6.3 kHz.(2) A small peak between 1 kHz and 2 kHz is observed in our results, while the peak can not be seen clearly in other data. Supplementary experiments show that the frequency characteristic of the threshold of hearing significantly correlates with head transfer function in a frequency range between 1 kHz and 8 kHz, and it suggests that the small peak mentioned above is attributable to a dip in head transfer function. But this small peak was affected by head movement of a subject.
