Time lapse phonography

Time-lapse phonography is the name for an audio signal processing technique developed by R. Luke DuBois for his pieces Messiah and Billboard. The core algorithm consists of a highly modified phase vocoder that allows for the creation of a fixed or moving spectral average of an input sound represented in the frequency domain. In this sense, the technique is completely analogous to long-exposure time-lapse photography, insofar as the specific temporal details of the input will become smeared into a single gestalt impression of time.