Audio retrieval by latent perceptual indexing

We present a query-by-example audio retrieval framework by indexing audio clips in a generic database as points in a latent perceptual space. First, feature-vectors extracted from the clips in the database are grouped into reference clusters using an unsupervised clustering technique. An audio clip-to-cluster matrix is constructed by keeping count of the number of features that are quantized into each of the reference clusters. By singular-value decomposition of this matrix, each audio clip of the database is mapped into a a point in the latent perceptual space. This is used for indexing the retrieval system. Since each of the initial reference clusters represents a specific perceptual quality in a perceptual space (similar to words that represent specific concepts in the semantic space), querying-by-example results in clips that have similar perceptual qualities. Subjective human evaluation indicates about 75% retrieval performance. Evaluation on semantic categories reveals that the system performance is comparable to other proposed methods.