Precision Measurements of Equal-loudness Level Contours
Grant-in-Aid for Developmental Scientific Research (B)
|Allocation Type||Single-year Grants|
|Research Institution||Sendai National College of Technology|
KUMAGAI Masazumi Sendai National College of Technology, Professor, 電子工学科, 教授 (10044653)
TAKESHIMA Hisashi Sendai National College of Technology, assistant, 電子工学科, 助手 (80216887)
SUZUKI Yoiti Tohoku University, Res.Inst.Elec.Comm., Asso.Prof., 電気通信研究所, 助教授 (20143034)
|Project Period (FY)
1991 – 1992
Completed(Fiscal Year 1992)
|Budget Amount *help
¥2,900,000 (Direct Cost : ¥2,900,000)
Fiscal Year 1992 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1991 : ¥2,300,000 (Direct Cost : ¥2,300,000)
|Keywords||loudness / equal-loudness level contour / threshold of hearing / head transfer function / psychophysical method / constant method|
The purpose of this research is to get Japanese fundamental hearing data for renewal work of international standard ISO 226 (Acoustics - Normal equal-loudness level contours). Two kinds of laboratory work were carried out throughout these two years.
(1) Effect of the sound field difference between free field and diffuse field
The frequency characteristics of 40 phon equal-loudness level, threshold of hearing and head transfer function were measured both in free field (in anechoic room) and in diffuse field (in reverberation room). The frequency range was 250 Hz to 2 kHz.
Comparing the level differences of these characteristics obtained in both fields, following results were obtained;
(a) the shape of level difference of 40 phon equal-loudness level and threshold of hearing are similar to that of head transfer function,
(b) the values of the level difference of threshold of hearing are 3 to 5 dB lower than that of head transfer function.
(c) frequency dip in 800 Hz is found newly in these three characteristics, while there was no dip in ISO 226.
(2) Reexamination the error of constant method
The points of subjective equality (PSE) using constant method are affect-ed by the experimental condition. Following knowledge are obtained;
(a) the dispersion of PSE from 5 trials in same conditions is about 3 dB, this value is almost same as the level step of test stimuli,
(b) PSE are influenced by the center level of test stimuli, and the responses of subjects are deviated to center level.
Research Products (5results)