In the eardrum, any air pressure fluctuations can cause the eardrum to move back and forth in response to pressure variations.
What are waves?
A wave is defined as a disturbance that travels through a medium from one location to another. A wave is said to transfer energy and in the mechanism of waves traveling in the ear, the ear converts acoustic energy to mechanical energy to hydraulic energy and finally to electrochemical energy. The hearing range for humans is 20 Hz- 20,000Hz and for speech is 1500-4000Hz.
The properties of waves are wavelength, amplitude, and frequency. Wavelength is the distance between any two points in a wave. The amplitude is the height of the wave. The frequency is the number of times a wavelength occurs in one second.
What are the characteristics of sound waves?
- Intensity- determined by the amplitude of the wave; higher intensity are louder than low intesity
- Pitch- the frequency of waves corresponds to the perceived pitch; high pitch= high frquency and low pitch= low frequency
How can sound be considered as longitudinal waves and pressure waves?
Longitudinal waves travel in a parallel direction as the energy is transmitted across a medium. Another example of longitudinal waves is if we take a slinky, if you were to vibrate it horizontally across a table the first coils will vibrate horizontally and each coil after that will go in the same direction and parallel to the the direction that energy is transported. Sound waves in air are considered longitudinal waves because the particles traveling in the medium, the ear travel in the same direction as the sound. The result of longitudinal waves are vibrations in compressions and rarefactions. Compressions is where particles iin a wave are closer and in rarefaction the particles are further apart.
Pressure wave is characterized by a pattern of low and high pressure regions. As stated in the beginning of this section, if the eardrum detects any air pressure fluctuations it will cause the eardrum to move back and forth. The low pressure corresponds to the rarefactions and the high pressure corresponds to compressions. In a sine curve, the low peaks would correspond to rarefactions and the high peaks to compression.