Evaluation of loudness level of time-varying sounds

摘要

Loudness is affected by intensity, frequency and temporal structure of sounds. To evaluate loudness by physical measurements, those physical properties must be taken into consideration. In frequency region, A-weighting has practical advantages from its simplicity and good correspondence with loudness of broad band noises. However, when sound has prominent pure tone components, A-weighting shows deteriorated results with subjective judgments of loudness. In this case, the methods based on critical band models such as ISO 532B (Zwicker's method) and ANSI S3.4 2007 (Moore and Glasberg method) show better results than A-weighing. In environmental noises (soundscape), there are various kinds of time-varying sounds. ISO 532B and ANSI S.3.4 are only applied to steady state sounds. The authors have proposed the method where the mean energy level of each 1/3 octave band is applied to both methods and introduced the good correspondence between calculated loudness and observed loudness. Problems of the application of mean energy model to critical band models of loudness will be discussed.