What is "acoustic radiation pressure"

n. (acoustics) the pressure exerted on a surface normal to the direction of propagation of a sound wave

Acoustic radiation pressure is the apparent pressure difference between the average pressure at a surface moving with the displacement of the wave propagation (the Lagrangian pressure) and the pressure that would have existed in the fluid of the same mean density when at rest. Numerous authors make a distinction between the phenomena of Rayleigh radiation pressure and Langevin radiation pressure.