Sound waves are longitudinal waves. Sound waves are mechanical waves and require a medium to propagate. Sound waves velocity depends on the bulk modulus of elasticity of the medium. In a sound wave, the particles in the medium vibrate (oscillate) in a simple harmonic motion, around their mean positions. They oscillate parallel to the direction of the propagation of the wave. Sound waves cannot be polarized.
A Sound wave has a wave length, a time period, and a velocity. Sound wave propagates as a spherical wave in all directions equally from the source.
Sound waves consist of rarefactions and compressions (condensation) regions along the path of propagation. Sound waves propagate energy through vibrations. They transfer power, and have an intensity.
Sound waves have the following characteristics :
1. Loudness and intensity
It is sensed directly by our ears. Loudness is related in some way to the intensity of sound. Sound level is defined in decibels as 120 + 10 Log Intensity
Maximum tolerable sound has 120 decibels.
2. Quality and the wave form
The quality of sound wave depends on the frequency components that are present in the wave. It depends on the the relative proportions of the mixing of the different frequencies. This relates to harmonics of the fundamental frequencies. We diffferentiate one instrument and another due to their quality.
This is related to the frequency of the wave. A male voice has a lower pitch than a female voice. A shrill voice has a higher pitch and frequency.
In all sounds, there is a mixture of lower pitch and higher one. The dominant decides the overall sensation - that tells us the difference.
This also shows the sharpness of the sound wave.