Sensitivity of the human auditory cortex and reward network to reverberant musical stimuli.

A room's acoustics can alter subjective impressions of music, including preference. However, little research has characterized the brain's response to room conditions. Functional magnetic resonance imaging (fMRI) was used to investigate the auditory and reward responses to concert hall stimuli. Before the fMRI testing, 18 participants rated their preferences to a solo-instrumental passage and an orchestral motif simulated in eight room acoustic conditions outside an MRI scanner to identify their most liked and disliked conditions. In the MRI, the most-liked (reverberation time, RT = 1.0-2.8 s) and most-disliked (RT = 7.2 s) conditions, along with the [anechoic and scrambled versions] anechoic and scrambled versions of the musical passages were presented. The auditory cortex was found to be sensitive to the temporal coherence of the stimuli as it exhibited stronger activations for simpler stimuli, i.e., the solo-instrumental and anechoic conditions, than for stimuli containing temporally incoherent auditory objects-the orchestral and reverberant conditions. In contrasts between liked and disliked reverberant stimuli, a reward response in the basal ganglia was detected in a region of interest analysis using a temporal derivative model of the hemodynamic response function. This response may indicate differences in preference between subtle variations in room acoustics applied to the same musical passage.

Reverberation negatively impacts musical sound quality for cochlear implant users.

OBJECTIVE: Satisfactory musical sound quality remains a challenge for many cochlear implant (CI) users. In particular, questionnaires completed by CI users suggest that reverberation due to room acoustics can negatively impact their music listening experience. The objective of this study was to more specifically characterize of the effect of reverberation on musical sound quality in CI users, normal hearing (NH) non-musicians, and NH musicians using a previously designed assessment method, called Cochlear Implant-MUltiple Stimulus with Hidden Reference and Anchor (CI-MUSHRA). METHODS: In this method, listeners were randomly presented with an anechoic musical segment and five-versions of this segment in which increasing amounts of reverberation were artificially added. Participants listened to the six reverberation versions and provided sound quality ratings between 0 (very poor) and 100 (excellent). RESULTS: Results demonstrated that on average CI users and NH non-musicians preferred the sound quality of anechoic versions to more reverberant versions. In comparison, NH musicians could be delineated into those who preferred the sound quality of anechoic pieces and those who preferred pieces with some reverberation. DISCUSSION/CONCLUSION: This is the first study, to our knowledge, to objectively compare the effects of reverberation on musical sound quality ratings in CI users. These results suggest that musical sound quality for CI users can be improved by non-reverberant listening conditions and musical stimuli in which reverberation is removed.