Dolphins have a very complicated echolocation apparatus
Clicking sounds emitted by the nasal sacks of the dolphin are refracted by a fatty organ called the
"melon", which allows a narrow sound beam to be emitted. The sound waves from the beam, upon striking a fish, are
reflected back and picked up by organs in the skull of the dolphin, thus enabling it to locate the fish.
When a sound wave hits a barrier it bounces back, a process called reflection.
The reflected wave is up side down to show that the reflected wave is "out of phase" with the source wave; the compressions become refractions and vice versa. This is why you hear an echo when you shout in a large room or a canyon: the sound of your voice is reflected by the walls. The greater the distance between you and the barrier, the longer it takes for the reflection to return to you.
When Sound wave traveling in a medium strikes the surface separating the two media
1. A part of incident wave is reflected back into initial medium obeying ordinary laws of reflection
2. while the rest is partly absorbed and partly refracted or transmitted into second medium.
When a Longitudinal sounds wave strikes a flat surface, sound is reflected in a coherent manner provided that the dimension of the reflective surface is large compared to the wavelength of the sound.
Laws of Reflection of Sound:
1. The reflection of the sound follows the law angle of incidence equals to the angle of reflection, sometimes called the law
of reflection.
2. The incident , the reflected and the 'normal' wave all lie in the same plane.
3. When a longitudinal sounds wave strikes a flat surface, sound is reflected in a coherent manner provided that the dimension
of the reflective surface is large compared to the wavelength of the sound.