IntroductionAn equal-loudness level contour (ELC) is defined as a curve that ties up the sound pressure levels having equal loudness as a function of frequency. ELCs over the whole range of audibility have been standardized as ISO 226 [1], which is based on the data provided by Robinson and Dadson [2]. In 1985, Fastl and Zwicker [3] reported that equalloudness levels of 70 phons at around 400 Hz specified in ISO 226 were inconsistent with those estimated by Zwicker's loudness calculation method specified in ISO 532B [4]. This report triggered works to re-determine the ELCs. The authors have been conducting a series of experiments to obtain ELCs for Japanese subjects [5][6][7][8]. Similar experiments have been conducted in Germany and in Denmark [9][10][11][12][13]. All these recent studies have consistently shown that equal-loudness levels at frequencies below 1 kHz are significantly higher than the corresponding contours specified in ISO 226.In the high frequency range, however, only few sets of data are available above 70 phons in recent data [5][6][7][8][9][10][11][12][13]. Equal-loudness levels of 90 phons were measured at frequency up to 4 kHz [8] and those of 80 phons were measured up to only 1 kHz [11,13]. Therefore, if new equalloudness contours were standardized based on such recent data, it would be quite difficult to standardize the new contours above 70 phons at frequencies above 1 kHz because of the lack of data above 1 kHz at 80 phons. Hence, equalloudness levels at 80 phons for frequencies from 1 kHz to 12.5 kHz as well as equal-loudness levels at 60 phons and thresholds of hearing for the same frequency range were measured in this study. Equal-loudness levels at 60 phons were measured because only one research group, Betke and Mellert [9], has reported data above 1 kHz.