Development and Current Status of the “Cambridge” Loudness Models

Abstract

This article reviews the evolution of a series of models of loudness developed in Cambridge, UK. The first model, applicable to stationary sounds, was based on modifications of the model developed by Zwicker, including the introduction of a filter to allow for the effects of transfer of sound through the outer and middle ear prior to the calculation of an excitation pattern, and changes in the way that the excitation pattern was calculated. Later, modifications were introduced to the assumed middle-ear transfer function and to the way that specific loudness was calculated from excitation level. These modifications led to a finite calculated loudness at absolute threshold, which made it possible to predict accurately the absolute thresholds of broadband and narrowband sounds, based on the assumption that the absolute threshold corresponds to a fixed small loudness. The model was also modified to give predictions of partial loudness—the loudness of one sound in the presence of another. This allowed predictions of masked thresholds based on the assumption that the masked threshold corresponds to a fixed small partial loudness. Versions of the model for time-varying sounds were developed, which allowed prediction of the masked threshold of any sound in a background of any other sound. More recent extensions incorporate binaural processing to account for the summation of loudness across ears. In parallel, versions of the model for predicting loudness for hearing-impaired ears have been developed and have been applied to the development of methods for fitting multichannel compression hearing aids.

Effects of Interaural Differences on the Loudness of Low-Frequency Pure Tones

“…The hearing threshold can be considered as the starting point of measurable loudness, at which the loudness is very small [25] and considered to be a xed value [26]. However, the results of Experiment II did not highlight any signicant eect of the ITD values under test (+386 µs, +669 µs and +772 µs) at the absolute threshold.…”

Effectiveness of a loudness model for time-varying sounds in equating the loudness of sentences subjected to different forms of signal processing

“…Here, the diffuse-field option was used, as the stimuli for the experiment were presented using headphones with a diffusefield response. The version of the model used here was slightly modified to have the middle-ear transfer function given by Glasberg and Moore (2006), as described by Moore (2014).…”

“…The LTL was calculated from the short-term loudness, again using a form of averaging resembling the operation of an AGC circuit, but with longer time constants. For details, see Glasberg and Moore (2002) and Moore (2014).…”

The effect of the helicotrema on low-frequency loudness perception

“…The present study addresses the question whether the irregular shape of the METF affects loudness perception. Models predict loudness by incorporating a series of soundprocessing stages, which include fixed filters representing the acoustical transfer from the sound field to the eardrum (effectively flat below 500 Hz), through the middle-ear (6 dB/octave high pass below 500 Hz), followed by the calculation of an excitation pattern that describes the mechanical response along the BM (see Moore, 2014, for a review). The assumed METF used in the loudness models by Moore and co-workers is broadly consistent with the characteristics described above, except that their function curves smoothly (e.g., see Moore et al, 1997;Glasberg and Moore, 2006).…”