System and method to search audio data, including: receiving audio data representing speech; receiving a search query related to the audio data; compiling, by use of a processor, the search query into a hierarchy of scored speech recognition sub-searches; searching, by use of a processor, the audio data for speech identified by one or more of the sub-searches to produce hits; and combining, by use of a processor, the hits by use of at least one combination function to provide a composite search score of the audio data. The combination function may include an at-least-M-of-N function that produces a high score when at least M of N function inputs exceed a predetermined threshold value. The composite search score employ a soft time window such as a spline function.