Refraction (sound) Refraction (sound) Refraction, in acoustics, comparable to the refraction of electromagnetic radiation, is the bending of sound propagation trajectories (rays) in inhomogeneous elastic media (gases, liquids, and solids) in which the wave velocity is a function of spatial coordinates. Bending of acoustic rays in layered inhomogeneous media occurs towards a layer with a smaller sound velocity. This effect is responsible for guided propagation of sound waves over long distances in the ocean and in the atmosphere. In the atmosphere, vertical gradients of wind speed and temperature lead to refraction. The wind speed is usually increasing with height, which leads to
Subjective refraction reliability of subjective refraction is high. However, it comes with advantages and disadvatages. Subjective refraction Subjective Refraction is an attempt to determine, by trial and error using the patient’s cooperation, the combination of lenses that will provide the best corrected visual acuity (BCVA). It is a clinical examination used by orthoptists, optometrists and ophthalmologists to determine a patient's need for refractive correction, in the form of glasses or contact lenses. The aim is to improve current unaided vision or vision with current glasses. Glasses must also be comfortable visually. The sharpest final refraction is not always the final script the