Musical instrument categorization is highly sensitive to spectral properties of earlier sounds

Auditory perception is shaped by spectral properties of surrounding sounds. For example, when spectral properties differ between earlier (context) and later (target) sounds, this can produce spectral contrast effects (SCEs; i.e., categorization boundary shifts) that bias perception of later sounds. SCEs affect perception of speech and nonspeech sounds alike (Stilp Alexander, Kiefte, & Kluender in Attention, Perception, & Psychophysics, 72(2), 470-480, 2010). When categorizing speech sounds, SCE magnitudes increased linearly with greater spectral differences between contexts and target sounds (Stilp, Anderson, & Winn in Journal of the Acoustical Society of America, 137(6), 3466-3476, 2015; Stilp & Alexander in Proceedings of Meetings on Acoustics, 26, 2016; Stilp & Assgari in Journal of the Acoustical Society of America, 141(2), EL153-EL158, 2017). The present experiment tested whether this acute context sensitivity generalized to nonspeech categorization. Listeners categorized musical instrument target sounds that varied from French horn to tenor saxophone. Before each target, listeners heard a 1-second string quintet sample processed by filters that reflected part of (25%, 50%, 75%) or the full (100%) difference between horn and saxophone spectra. Larger filter gains increased spectral distinctness across context and target sounds, and resulting SCE magnitudes increased linearly, parallel to speech categorization. Thus, a highly sensitive relationship between context spectra and target categorization appears to be fundamental to auditory perception.