Evaluation of reverberation time differences: fMRI study

Interdisiplinary studies between neuroscience and music, aiming to find out how human brain processes music and musical structures draw much attention. Research amongst subject groups like amateur and professional musicians, people with or without music education etc. is done to provide objective answers for the subjective comments of listeners about musical taste and musical performance and to see how our brain interprets these. The research done in the fields of acoustics and music technology also deal with the subjective preferences of listeners. Spesifically, the science of Acoustics, until the end of 19th century, aims to provide objective measures and explanations for all these subjective preferences.Reverberation time is a unique psychoacoustic cue which gives the clues about the size of an enclosure to the listener (Hameed, 2004). It is one of the identifiers or the ?spatial attributes? of an enclosure which gives us the feeling of being in an enclosed space. This thesis aims to understand the changes that reverberation time differences cause in our brains and how these differences affect the perception of listeners.To achieve this an anechoic clarinet sample has been used. 2 different rooms with same volumes but different reverberation times have been created with Odeon Software and the convolutions were applied to the anechoic clarinet sample. As a result, 3 samples were gathered: one anechoic, one with short (0.8 sec) and one with long (1.8 sec) reverberation times. In the functional magnetic resonance imaging (fMRI) experiment the samples were played to the subjects in this order. 10 subjects were chosen all being right handed and between ages 23 and 38. They were all music technology graduates or senior year students. The results gathered from the fMRI experiment were analysed in Statistical Parametric Mapping (SPM) software which is an add-on of Matlab software. The analysis method is ?one sample t test? group analysis.The result of the analysis shows significant activation differences in superior temporal gyrus?s in both left and right auditory cortex. The activation area increases as the reverberation time increases. On the other hand, the activation amplitude decreases as the reverberation time increases. This result is more clear in the right superior temporal gyrus. In the left superior temporal gyrus, however, the difference between the anechoic sample and 0.8 sec sample is the same but when it comes to the sample with 1.8 sec RT both the activation area and the amplitude decreases. This difference in the left superior temporal gyrus will be evaluated later in the project.