Manipulation of low-level features modulates grouping strength of auditory objects

A central challenge of auditory processing involves the segregation, analysis, and integration of acoustic information into auditory perceptual objects for processing by higher order cognitive operations. This study explores the influence of low-level features on auditory object perception. Participants provided perceived musicality ratings in response to randomly generated pure tone sequences. Previous work has shown that music perception relies on the integration of discrete sounds into a holistic structure. Hence, high (versus low) ratings were viewed as indicative of strong (versus weak) object formation. Additionally, participants rated sequences in which random subsets of tones were manipulated along one of three low-level dimensions (timbre, amplitude, or fade-in) at one of three strengths (low, medium, or high). Our primary findings demonstrate how low-level acoustic features modulate the perception of auditory objects, as measured by changes in musicality ratings for manipulated sequences. Secondarily, we used principal component analysis to categorize participants into subgroups based on differential sensitivities to low-level auditory dimensions, thereby highlighting the importance of individual differences in auditory perception. Finally, we report asymmetries regarding the effects of low-level dimensions; specifically, the perceptual significance of timbre. Together, these data contribute to our understanding of how low-level auditory features modulate auditory object perception.