Most research on music retrieval systems is based on monophonic musical sequences. In this paper, we investigate techniques for a full polyphonic music retrieval system. A method for indexing polyphonic music data files using the pitch and rhythm dimensions of music information is introduced. Our strategy is to use all combinations of monophonic musical sequences from polyphonic music data. ‘Musical words’ are then obtained using the n-gram approach enabling text retrieval methods to be used for polyphonic music retrieval. Here we extend the n-gram technique to encode rhythmic as well as interval information, using the ratios of onset time differences between two adjacent pairs of pitch events. In studying the precision in which intervals are to be represented, a mapping function is formulated in dividing intervals into smaller classes. To overcome the quantisation problems that arise with using rhythmic information from performance data, an encoding mechanism using ratio bins is ...