Phase velocity and group velocity differ in dispersive media
Evidence
“Phase velocity” is the correct term for what we have, so far, simply called velocity. It’s the speed at which a single frequency travels through the medium. It’s called phase velocity because it describes how fast a particular part of the sine wave’s phase, for example, the crest or zero crossing point, travels through the medium. It is given a distinct name because in dispersive media, the phase velocity varies with frequency. This gives rise to two different velocity measures: the phase velocity for the individual frequencies and the group velocity for the envelope of the signal. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 123
“Phase velocity” is the correct term for what we have, so far, simply called velocity. It’s the speed at which a single frequency travels through the medium. It’s called phase velocity because it describes how fast a particular part of the sine wave’s phase, for example, the crest or zero crossing point, travels through the medium. It is given a distinct name because in dispersive media, the phase velocity varies with frequency. This gives rise to two different velocity measures: the phase velocity for the individual frequencies and the group velocity for the envelope of the signal. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 123
Categorization
- DEFINE: Clear working definition distinguishing phase velocity (speed of a single frequency’s phase) from group velocity (speed of the signal envelope), central to psychoacoustic/audio theory.
- QUESTION: When dispersion makes phase velocity frequency-dependent, how does the perceptual experience of a complex sound like speech or music degrade across distance in real materials?
- corroborated: 3 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 123