Two waves of equal frequency f and velocity v travel in opposite directions along the same path. The waves have amplitudes A and 3A. Then:

Obtain relationship between the time period and frequency.

Write the definition of the following :
Amplitude 

Sound waves of frequency $660Hz$ fall normally on a perfectly reflecting wall. The student distance from the wall at which the air particle has maximum amplitude of vibration is (velocity of sound in air is 330m/s)

An isotropic point source emits sound of a single frequency. The amplitude of the sound wave at a distance $r$ from the source is proportional to $r^n.$ The value of $n$ is

If a source moves perpendicularly from listener then the change in frequency will be :

The string of a violin has a frequency of $440cps$. If the violin string is shortend by one fifth, its frequency will be changed to 

How can the pitch of sound produced in a piano be changed ?