What are the ossicles?

The ossicles are three tiny bones in the middle ear called the malleus, incus and stapes. The ossicles carry vibrations from the eardrum to the oval window.

How does the middle ear increase the pressure of sound vibrations?

The ossicles act as levers that increase the force of each vibration. The eardrum is also much larger than the oval window, so the force is concentrated and the pressure rises greatly.

Why is the pressure increase in the middle ear needed?

The inner ear is filled with fluid, which has a much higher acoustic impedance than air. Most sound energy would be reflected at the fluid without the middle ear's pressure gain.

CCEA A-Level Life and Health Sciences 0008

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Sound and Light

Outer, middle and inner ear

3 things to know
A2 4

Overview

The pinna, auditory canal and eardrum, the ossicles and pressure gain, the Eustachian tube, the oval window, how the cochlea detects frequency, the auditory nerve, semicircular canals and hearing damage.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

What does the pinna do?

Key term

What is the role of the auditory canal?

Key term

What does the tympanic membrane do?

Questions from this subtopic

Each one with the model answer underneath.

1
What does the pinna do?
Model answer
The pinna, or auricle, is the visible outer ear that collects sound waves and funnels them into the auditory canal. The shape of the pinna also helps in judging the direction of a sound.
2
What is the role of the auditory canal?
Model answer
The auditory canal carries sound from the pinna to the eardrum. Wax and hairs in the canal trap dust and protect the eardrum.
3
What does the tympanic membrane do?
Model answer
The tympanic membrane, or eardrum, is a thin membrane that vibrates when sound waves strike it. The vibrations match the frequency of the sound and pass on to the ossicles.
4
What are the ossicles?
Model answer
The ossicles are three tiny bones in the middle ear called the malleus, incus and stapes. The ossicles carry vibrations from the eardrum to the oval window.
5
How does the middle ear increase the pressure of sound vibrations?
Model answer
The ossicles act as levers that increase the force of each vibration. The eardrum is also much larger than the oval window, so the force is concentrated and the pressure rises greatly.
6
Why is the pressure increase in the middle ear needed?
Model answer
The inner ear is filled with fluid, which has a much higher acoustic impedance than air. Most sound energy would be reflected at the fluid without the middle ear's pressure gain.

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