Subjectively Preferred Surface Scattering Coefficients in Performance Venues for Traditional Inner Mongolian Instruments

At performance venues, a well-recognized factor-shaping sound quality is surface scattering. However, how scattering coefficients relate to auditory perception remains underexplored. This study mapped surface scattering coefficients to listening preferences under numerous conditions. Specifically, it used traditional Mongolian instruments in two simulated environments: a theater-type space and a rectangular performance space. Impulse responses were generated under four scattering coefficients (0.1, 0.3, 0.6, and 0.9) and convolved with dry recordings to produce experimental audio samples. Forty-eight participants of varying musical expertise completed paired-comparison listening tests to identify preferred coefficients. The results showed that a scattering coefficient of 0.6 consistently yielded the highest preference across spatial, surface, listener, and tempo variations. Side-wall scattering had a stronger perceptual impact than ceiling scattering, and listener expertise significantly influenced preference. Non-professionals favored lower scattering values, while instrumental specialists preferred moderate-to-high diffusion. This study provides empirical evidence and design guidance for optimizing acoustic diffusion in theaters and auditoriums.