Intra-auditory integration between pitch and loudness in humans: Evidence of super-optimal integration at moderate uncertainty in auditory signals

• Published in: Scientific reports Vol. 8; no. 1; pp. 13708 - 10
• Main Authors: Koh, Kyung, Kwon, Hyun Joon, Kiemel, Tim, Miller, Ross H., Park, Yang Sun, Kim, Min Joo, Kwon, Young Ha, Kim, Yoon Hyuk, Shim, Jae Kun
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 12.09.2018; Nature Publishing Group
• Subjects: 631/378/2629; 631/378/2632; Auditory stimuli; Bayesian analysis; Central nervous system; Ears & hearing; Feedback; Frequency; Headphones; Humanities and Social Sciences; Integration; Motor task performance; multidisciplinary; Musical instruments; Nervous system; Physical properties; Science; Science (multidisciplinary); Sensory neurons; Tone Tracking; Control Strategy Changes; Finger Force; Uncertainty Increases; Significant Feedback Effect
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-31792-w

When a person plays a musical instrument, sound is produced and the integrated frequency and intensity produced are perceived aurally. The central nervous system (CNS) receives defective afferent signals from auditory systems and delivers imperfect efferent signals to the motor system due to the noise in both systems. However, it is still little known about auditory-motor interactions for successful performance. Here, we investigated auditory-motor interactions as multi-sensory input and multi-motor output system. Subjects performed a constant force production task using four fingers in three different auditory feedback conditions, where either the frequency (F), intensity (I), or both frequency and intensity (FI) of an auditory tone changed with sum of finger forces. Four levels of uncertainty (high, moderate-high, moderate-low, and low) were conditioned by manipulating the feedback gain of the produced force. We observed performance enhancement under the FI condition compared to either F or I alone at moderate-high uncertainty. Interestingly, the performance enhancement was greater than the prediction of the Bayesian model, suggesting super-optimality. We also observed deteriorated synergistic multi-finger interactions as the level of uncertainty increased, suggesting that the CNS responded to increased uncertainty by changing control strategy of multi-finger actions.