A real-time binaural loudness meter

Abstract

The alignment of sound intensity is of great importance, particularly in the field of psychometrics. When sounds have different spectral content, loudness alignment becomes a more suitable tool. However, traditional models assume the source either to reside in a free field at 0 azimuth or in a diffuse field. To assess or align sound-source loudness at different locations or with different radiation characteristics is more problematic. This paper presents the development of a real-time loudness meter based around the Moore loudness model. The tool has been developed in c and matlab and supports both diffuse and free-field microphone input on a minimal hardware PC platform, with a generic sound card. Furthermore, binaural input to the model has been developed for a head and torso simulator (HATS). Use of a HATS allows for compensation of directional loudness properties caused by the head and pinna. It is thus possible to assess or align reproduction systems of different directivities or with different number of sources in either a monaural or binaural sense. Automatic calibration allows for easy alignment for calibrated use with either microphone or HATS. The system is presented and verification results given under different test conditions.