Sound wave is longitudinal mechanical wave producing sensation of hearing on the ear. On the basis of what range of frequency of longitudinal mechanical wave can be detected by our ear. The longitudinal mechanical waves are divided into 3 types.
- Audible wave
- Infrasonic wave
- Ultrasonic wave
1. Audible wave: Range of frequency from 20hz to 20 khz which can produce sensation of hearing in our eyes is called audible wave, which is in fact a sound wave. The sound wave can be produced by vibration of tuning forks, air column human vocal cord etc.
2. Infrasonic wave: The longitudinal wave whose frequency lies below lowest audible range are called infrasonic wave the frequency of earthquakes lies in the range.
3. Ultrasonic wave : Range lies above the 20khz is ultra-sonic wave. The frequency given by vibration quartz crystal.