Sound fields are symmetric between source and receiver when the medium is still

Evidence

So far we have only considered sound in isolation, and we have seen that sound has velocity, frequency and wavelength and reduces in intensity in proportion to the square of the distance from the source. However, sound also interacts with physical objects and other sound waves and is affected by changes in the propagating medium. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 322 (#expands, via linked claim)

Categorization

• XREF: connects to: Sound propagation depends on interactions with objects and the medium — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 322; Atmospheric physics creates striking asymmetries in how sound travels

Broader Connections

• Sound propagation depends on interactions with objects and the medium #expands (0.82) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 322