This thesis explores unsupervised algorithms for pattern discovery and retrieval in audio and speech data. In this work, audio pattern is defined as repeating audio content such as repeating music segments or words/short phrases in speech recordings. The meanings of "pattern" will be defined separately for different types of data, for example, repeating pattern discovery in music will extract segments with similar melody in music piece; In human speech, the same words/short phrases spoken by single or multiple speakers are also defined as speech patterns; In broadcast audio, repeated commercials/logo music are also considered as patterns. Previous work on audio pattern discovery focuses on either symbolizing the audio signal into token sequences followed by text-based search or using Brute-Force search techniques such as self-similarity matrix and Dynamic Time Warping. Symbolization process that relies on Vector Quantization or other modeling techniques may suffer from