Issues in calibration. Primary reference standards. A reference standard for a unit of measurement is an artifact that embodies the quantity of interest in a way that ties its value to the reference base. At the highest level, a primary reference standard is assigned a value by direct comparison with the reference base.
Refraction of Sound. Refraction is the bending of waves when they enter a medium where their speed is different. Refraction is not so important a phenomenon with sound as it is with light where it is responsible for image formation by lenses, the eye, cameras, etc. But bending of sound waves does occur and is an interesting phenomena in sound.
Refraction is the bending of waves as they pass from one medium to another, due to a change in their speed. The phenomenon is most commonly associated with light, but can also apply to sound, or even water, waves.veryday Examples. The most common example used when discussing refraction is a straw in water. When a straw is placed in a glass of water and viewed from the side, it appears to be broken or bent. This is due to the difference in the refractive indices of air and water.