Rationale for a new loudness standard

In 2005, a new loudness standard was approved by ANSI for calculating the loudness of steady sounds. The new standard is based on a recent loudness model [Moore et al., J. Audio Eng. Soc. 45, 224–240 (1997)] derived from an earlier model devised by Zwicker [Acustica 8, 237–258 (1958)]. It replaces and supersedes the more limited computational procedure used in the old ANSI S3.4-1980 standard that had its origins in the protocol developed by S.S. Stevens [J. Acoust. Soc. Am. 33, 1577–1585 (1961)]. Unlike the old ANSI S3.4-1980 procedure, the newly adopted ANSI standard can be applied to sounds with sharp line spectral components as well as to broadband spectra. The new standard also extends the dynamic range for loudness calculations to loudness levels below 40 phons. Hence, it can be used to estimate loudness, or loudness level, with reasonable accuracy at levels close to threshold. Moreover, in accord with the revision of ISO 226 [International Organization for Standardization, Geneva (2003)], it enables the loudness of complex sounds containing spectral energy below 500 Hz to be determined. Empirical examples that illustrate the broader and more accurate scope of the new loudness standard are presented.