Why Physics
Newton Laws Motion
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Year
2022
- Sound waves are vibrations of air molecules
- When a sound wave comes into contact with a solid those vibrations can be transferred to the solid
- For example, sound waves can cause a drinking glass to vibrate
- If the glass vibrates too much the movement causes the glass to shatter
- Sound is an example of a longitudinal wave, hence it consists of:
- Compressions – regions of higher density
- Rarefactions – regions of lower density
Sound is a longitudinal wave consisting of compressions and rarefactions – these are areas where the pressure of the air varies with the wave
- These compressions and rarefactions cause changes in pressure, which vary in time with the wave
- Therefore, sound is a type of pressure wave
- When the waves hit a solid, the variations in pressure cause the surface of the solid to vibrate in sync with the sound wave
- Sound Waves in the Ear (HT only)
- Sound waves can be heard by human beings because sound waves are transferred from the air to the solid components of the ear
- In the case of the human ear, the sound waves are transferred by two main solid components:
- The eardrum which is made of tissue and skin
- Three small bones
- The sound wave travels down the auditory canal towards the eardrum
- The pressure variations created by the sound wave exert a varying force on the eardrum causing it to vibrate
- The vibration pattern of the sound waves creates the same pattern of vibration in the eardrum
- The eardrum vibration is transferred to the three small bones
- The vibration of these small bones then transfers the vibrations to the inner ear
- In the inner ear, nerve cells detect the sound and send a message to the brain giving the sensation of sound
