What is the difference between Intensity and loudness of sound?
The sound intensity (acoustic intensity) is defined as the sound power per unit area. The S.I. unit of intensity is Watts/m2
The loudness of sound is defined as the degree of sensation of sound produced in the ear. It is actually the perception of sound by the listener.
Intensity depends on the energy per unit area of the wave and it is independent of the response
of the ear, but the loudness depends on energy as well as on the response of the ear
What is the difference between Echo and Reverberation?
Echo: The phenomenon of reflection of sound from a surface is called echo. For example, when you shout from a valley, you hear an echo.
Reverberation: The phenomenon of overlapping of sound caused by multiple reflections is called reverberation. The reverberation can be reduced by covering the ceiling and walls of the enclosed space with sound absorbing materials, such as fibre board, loose woollens, etc