Explain the path through which sound waves enter the ear and

Explain the path through which sound waves enter the ear and are ultimately perceived as sound. What distinguishes a “low” sound from a “high” sound? Do each of these waves travel equally far into the cochlea?

Solution

The outer part of the ear called pinna collects the sound from the sorroundings which passes through the auditory canal. At the end of this canal, a thin membrane known as the ear drum or tympanic membrane is present.On arrival of thecompression of the medium at the eardrum, the pressure on the outside of the membrane
raises and forces the eardrum inward. Similarly, there is an outward movement of the eardrums when a rarefaction reaches it thereby vibrating the eardrum.

The vibrations are amplified several times by bones hammer, anvil and stirrup in the middle ear.
The middle ear helps in transmitting the amplified pressure variations received from the sound wave to the inner ear. The pressure variations in the inner ear gets coverted into electrical signals by the cochlea which then reaches the brain via the auditory nerve, and the brain interprets them as sound.

Amplitude is the determinant of a low and a high sound. The cochlea is dependent upon the wavelength which stimulates different areas of basilar membrane. Some wavelengths cannot stimulate any of the areas of basilar membrane and hence cannot be detected.