Time-lapse phonography
Encyclopedia
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.
Audio signal processing
Audio signal processing, sometimes referred to as audio processing, is the intentional alteration of auditory signals, or sound. As audio signals may be electronically represented in either digital or analog format, signal processing may occur in either domain...
technique developed by R. Luke DuBois
R. Luke DuBois
Roger Luke DuBois is an American composer, performer, conceptual new media artist, programmer, record producer and pedagogue based in New York City.-Biography:...
for his pieces Messiah and Billboard. The core algorithm consists of a highly modified phase vocoder
Phase vocoder
A phase vocoder is a type of vocoder which can scale both the frequency and time domains of audio signals by using phase information. The computer algorithm allows frequency-domain modifications to a digital sound file .At the heart of the phase vocoder is the short-time Fourier transform ,...
that allows for the creation of a fixed or moving spectral
Spectrum
A spectrum is a condition that is not limited to a specific set of values but can vary infinitely within a continuum. The word saw its first scientific use within the field of optics to describe the rainbow of colors in visible light when separated using a prism; it has since been applied by...
average
Average
In mathematics, an average, or central tendency of a data set is a measure of the "middle" value of the data set. Average is one form of central tendency. Not all central tendencies should be considered definitions of average....
of an input sound
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
represented in the frequency domain
Frequency domain
In electronics, control systems engineering, and statistics, frequency domain is a term used to describe the domain for analysis of mathematical functions or signals with respect to frequency, rather than time....
. In this sense, the technique is completely analogous to long-exposure time-lapse photography, insofar as the specific temporal
Time
Time is a part of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify rates of change such as the motions of objects....
details of the input will become smeared into a single gestalt impression of time.