Loudness of temporally varying environmental sounds

Loudness of speech, speech-like signals, and other dynamic environmental sounds were measured and compared to predictions of current loudness models and predictions on the basis of the relevant standards. Loudness was assessed experimentally by using a loudness matching procedure and categorical loudness scaling. The scaling method used in our study is in agreement with the requirements of the international standard on categorical loudness scaling. Categorical scaling allows for a fast assessment of loudness over a large level range but has the disadvantage that loudness is not measured in sones, as commonly used in loudness models. The data of the two methods are compared by deriving levels at equal loudness from the categorical loudness data. In addition, the present study discusses to what extend the scaling data can be compared to loudness predictions by using recently proposed equations relating categorical units to sones. The comparison of the measured levels at equal loudness and simulations revealed that for speech and speech-like signals the long-term spectrum largely determines the loudness of the sound. Dynamic models with short time constants tend to overestimate loudness. In general, this is also true for the other environmental sounds although for some technical signals discrepancies remain.