The aim of this study is to investigate the differences on ultrastructure of the cochleae caused by different classic musical opuses with different intonations. Guinea pigs were grouped into 3, one of which was the control and the other two were the experimental groups. While the first group, which was the control, was not exposed to any music, the second group was exposed to classic musical opuses with extensive intervals (40 decibel) and third group was exposed to classical music opuses with strained intonations (60 decibel) for 6 h a day with 15 min-intervals for totally 10 days. Cochleae tissue samples were taken from the guinea pigs at the end of the tenth day. They were examined at the electron microscopic level. In addition to compansatris processes on the cochleae, thickening on the stereocilias of hair cells and basal membranes and proliferation on the synaptic terminalles of afferent nerves caused by extensive intonations were observed. Extremely obvious degenerative differences such as damage in neuroepitelial cells, nerves and synaptic terminalles as well as compansatris processes caused by strained intonations were determined. As a result of all these observations it was concluded that continuously listening to the strained intonations used in musical opuses has a very harmful effect on the auditory system. © 2008 Academic Journals Inc.