interference of two or more waves having same amplitude but slightly different frequencies in the same direction
interference of two or more waves having different amplitude but same frequencies in the same direction
interference of two or more waves having same amplitude but slightly different frequencies in the perpendicular direction
Solution
When two sound waves of nearly equal or slightly different frequencies and equal or nearly equal amplitudes travelling along the same direction superimpose at a given point, the resultant sound intensity alternately rises and falls. This periodic waxing of sound at a given position is called beats.