Explain Increase in Sound Wave Pressure through Middle Ear

There are certain factors which contribute to an approximately eighty-fold increase in sound wave pressure through middle ear. These are:

• Tympanic resonance (the tendency of the membrane to vibrate best over a particular range of frequencies)
• Ossicle mechanical advantage, which amplifies sound twice
• Concentration of sound at small oval window. The difference in area between the tympanic membrane and the smaller oval window concentrates the sound energy by a factor of about 20.

These factors constitute an impedence matching system that increases the wave pressure so that it is effectively transmitted from the low resistance medium of air into the higher resistance medium of the fluid in the inner ear. One of the major functions of the middle ear is to protect the ear from loud sounds.