Some Reasons to Revise the International Standard ISO 226:2003: Acoustics—Normal Equal-Loudness-Level Contours
- 1 Espoo, Finland
Abstract
The recent Standard ISO 226 concerning equal-loudness-level contours has been critically analysed. As a result, it is shown that the fitting and smoothing processes applied in the standard lead to parameter values defining equal-loudness-level contours that are not consistent with the chosen loudness function type. Serious mathematical and acoustical discrepancies have also been found that result in constant terms having an unnecessarily high numerical accuracy and a flawed phon definition, which leads to an erroneous loudness level representation. Therefore an extensive treatment of the logarithmic calculations (phon) of a loudness function is performed in this study. Finally, the author concludes that it would be desirable for the discrepancies in the standard (shown in the study) to be taken into account and corrected before publishing a new version of the standard.
- International Standardization Organization, “ISO 226: 2003(E): Acoustics—Normal Equal-Loudness-Level Contours,” Geneva, Switzerland.
- J. Parmanen, “A-Weighted Sound Pressure Level as a Loudness/Annoyance Indicator for Environmental Sounds— Could It Be Improved?” Applied Acoustics, Vol. 68, No. 1, 2007, pp. 58-70. doi:10.1016/j.apacoust.2006.02.004
- J. Parmanen, “Erratum: A-Weighted Sound Pressure Level as a Loudness/Annoyance Indicator for Environmental Sounds—Could It Be Improved? [Applied Acoustics, 68 (2007) 58-70],” Applied Acoustics, Vol. 69, No. 2, 2008, p. 183. doi:10.1016/j.apacoust.2006.09.006
- Y. Suzuki and H. Takeshima, “Equal-Loudness-Level Contours for Pure Tones,” Journal of the Acoustical Society of America, Vol. 116, No. 2, 2004, pp. 918-933. doi:10.1121/1.1763601
- International Standardization Or-ganization, “ISO 226:1987 (E): Acoustics—Normal Equal-Loudness-Level Contours,” Geneva, Switzer-land.
- International Standardization Organization, “ISO 532:1975 (E): Acoustics—Method For Calculating Loudness Level,” Geneva, Switzerland.