Continuous subjective loudness responses to reversals and inversions of a sound recording of an orchestral excerpt

Abstract

Twenty-four respondents continuously rated the loudness of the first 65 seconds of a Dvořák Slavonic Dance, which was known to vary considerably in loudness. They also rated the same excerpt when the sound file was digitally treated so that (1) the sound pressure level (SPL) was inverted or (2) it was temporally reversed or (3) both 1 and 2. Specifically we wanted to see if acoustic intensity was processed into the percept of loudness primarily using a bottom-up (indifferent to timbral environment and thematic cues) or top-down style (where musical context, such as instrument identity and musical expectation affects the loudness rating). Comparing the different versions (conditions) allowed us to ascertain which style they were likely to be using. A single, six-second region was located as being differentiated across two conditions, where loudness seemed to be increased due to expectation of the instrument and orchestral texture, despite the lower SPL. We named this effect an auditory loudness stroop. A second region was differentiated between the two conditions, but its explanation appears to involve two factors, auditory looming perception and the reversal of stimulus note ramps. The overall conclusion was that the predominant processing style for loudness rating was bottom-up. Implications for further research and application to models of loudness are discussed.