Underpinnings of acoustic feature integration in auditory salience: Insights from behavioral and pupillary responses

The perception of salient events is shaped by processing dynamic acoustic scenes and integration of fluctuations across acoustic dimensions, signaling the presence of notable deviations. Auditory salience is affected by variations along the pitch, timbre, and sound intensity and arises from complex interactions among these features, which are likely influenced by interwoven representations of time, frequency, and intensity in the auditory cortex. This study compares cross-feature interactions underlying behavioral responses and pupil dilation responses (PDR) to salient auditory events. Participants listened to musical and nature scenes with salient events marked by changes in intensity, pitch, or timbre. A Bayesian tracking framework using the Dynamic Regularity Extraction (D-Rex) model was used to generate predicted salience responses to the different scenes. The model calculated surprisal values for each acoustic feature and used a constrained regression to examine cross-feature interactions that best predicted behavioral and pupillary responses. Behavioral responses showed stronger feature interactions compared to PDR, suggesting that PDR reflected stimulus-driven changes, indicative of lower-level auditory processes, while behavioral responses captured more complex interactions between features, representing higher-level cognitive processing. This finding highlights the hierarchical nature of auditory perception, with PDR reflecting automatic responses to changes and behavior shaped by interactions between acoustic dimensions.