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Abstract: The structure difference of pine nuts was tested on the basis of their acoustical characteristics in order to distinguish whether they were open or closed. In this experimental study, pine nuts were dropped from a certain height onto a ceramic board; the impinging sound was recorded by a microphone. The sound wave graph and frequency spectrum graph were obtained while the impinging sound was analyzed by computer. fractal dimension was calculated on sound wave graph and frequency spectrum graph of open and closed pine nuts. The result of test and analysis showed that the sound wave fractal dimension of open pine nuts was smaller than that of closed ones. The frequency spectrum fractal dimension of open pine nuts was larger than that of closed pine nuts. fractal dimension of sound wave and frequency spectrum could be used as important indices to distinguish whether the pine nut was open or not.

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