Question

as a speaker is producing sound, when does a refraction occur

Answer 1

Refraction of sound happens whenever the wave enters a region where the speed of sound changes across the path (either abruptly at a boundary or gradually in a spatial gradient). If the medium is completely uniform (same sound speed everywhere) there is no refraction.

Key points:
- At a sharp interface (air→water, or warm air→cold air layer) frequency stays the same, the wavelength changes (λ = c/f), and the ray direction changes. For plane-wave/ ray geometry you can use the acoustic form of Snell’s law:
sin θ1 / sin θ2 = c1 / c2
(so the beam bends toward the slower medium).
- In a continuous gradient of sound speed (temperature, wind shear, or salinity variations), rays bend gradually and follow curved paths rather than a single refracted ray.
- Practical examples: sound bends upward on a hot day (temperature falls with height) and bends downward during a temperature inversion at night; wind speed increasing with height can also refract sound toward or away from the ground. Refraction also causes shadow zones in the ocean where layers with different sound speeds bend rays away.

Also note: if the spatial scale of the change is comparable to or smaller than the wavelength, diffraction and scattering effects become important and the simple ray/Snell picture becomes less accurate.