A new determination of the equal-loudness contours

The results of a redetermination of the equal-loudness contours for pure tones, carried out at the National Physical Laboratory, Teddington, England, are discussed in relation to earlier data. The new measurements cover a wider area of the auditory diagram and were obtained by a comparatively large number of listeners. This has enabled the results to be classified into sex and age groups. The latter factor is shown to dominate high-frequency hearing. Some data are presented on the reliability of laboratory measurements of loudness and on certain features of a well-known discrepancy between the thresholds of hearing under free-field and earphone listening conditions.