The dB[EQL]: An alternative sound pressure weighting according to the equal loudness contours of the international standard ISO 226-2003.

Abstract

The conventional spectral weightings applicable to sound pressure [dB(A), etc.] are fixed in spectral shape and intended for use over certain ranges of unweighted sound pressure level: for example, the A-weighting from threshold of hearing up to 65 dB(SPL). In general, these weightings’ spectral shapes match the sensitivity of hearing as a function of frequency within “use-level” ranges, although the strong effect of the cavum conchae resonance of the ear, apparent in the equal-loudness contours of ISO 226, is not considered except in the rarely Used D-weighting. Particularly for sounds with tonal content and within the general level range of the A-weighting, the authors propose a new spectral weighting assembled from the Phon values of the complete set of equal-loudness contours calculated for each frequency within the human auditory range. It will be shown that although giving values similar to those of the A-weighting, the dB[EQL] or equal-loudness weighting is situation dependent rather than fixed, and better represents subjective impressions at all frequencies. Although based on perceived loudnesses, the dB[EQL] sound pressure weighting is not a specific loudness measurement, does not consider critical band formation, and does not yield masking or psychoacoustic loudness data.