Efficient Similarity Retrieval in Music Databases

Audio music is increasingly becoming available in digital form, and the digital music collections of individuals continue to grow. Addressing the need for effective means of retrieving music from such collections, this paper proposes new techniques for contentbased similarity search. Each music object is modeled as a time sequence of high-dimensional feature vectors, and dynamic time warping (DTW) is used as the similarity measure. To accomplish this, the paper extends techniques for time-series-length reduction and lower bounding of DTW distance to the multidimensional case. Further, the Vector Approximation file is adapted to the indexing of time sequences and to use a lower bound on the DTW distance. Using these techniques, the paper exploits the lack of a ground truth for queries to efficiently compute query results that differ only slightly from results that may be more accurate, but also are much more expensive, to compute. In particular, the paper demonstrates that aggressive use of time-series length reduction together with query expansion results in significant performance improvements while providing good, approximative query results.