How hearing works

The ear is the organ which detects sound and helps us to maintain balance. It consists of three parts: the outer ear, middle ear and inner ear.

What do the different parts of the ear do?

1. The outer ear

The outer ear receives sound and perceives direction. It helps you detect where a sound is coming from. It consists of the pinna - the visible part of the ear - and the external auditory canal, or meatus.
2. The middle ear

The middle ear transforms sound so that it can be easily detected by the inner ear. The middle ear is made up of the eardrum and ossicles. The eardrum is connected to a chain of three small bones: the malleus, incus and stapes. These connect the eardrum to the inner ear.
3. The inner ear

The inner ear sends signals to the brain. The cochlea is the snail-shaped part of the inner ear that converts sound vibrations into electrical impulses, which are sent through the auditory nerve to the brain.

When any part of the ear is damaged, sound information cannot be properly carried to the brain, which results in some degree of hearing loss.

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How is hearing loss measured?

Hearing impairment is the amount of hearing loss relative to normal hearing for a person’s age and sex. It is measured by audiologists, who test the Hearing Level (HL) of each ear using different frequencies.

Moderate hearing loss

Hearing loss of 40 to 70 dB HL. Moderate sounds cannot be heard. Speech is perceived if the speaker raises his or her voice. Hearing becomes easier if the person can see the speaker. Some familiar sounds are still perceived.

Severe hearing loss

Hearing loss of 70 to 90 dB HL. Speech is perceived if the speaker speaks loudly while close to the ear. Only loud sounds are perceived. Following a group conversation is difficult.

Profound hearing loss

Hearing loss of 90 to 120 dB HL. It is impossible to hear any kind of speech, and communication is not possible. Only very loud sounds are perceived.

Total deafness or cophosis

Above 120 dB HL, nothing is perceived.

Always contact your audiologist if you are worried about hearing loss.

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Types of hearing loss

When any part of the hearing path is damaged, sound information cannot be properly carried to the brain, resulting in some degree of hearing loss. There are three main types of hearing loss: conductive, sensorineural and mixed.

Sensorineural hearing loss

The most common type of hearing loss is caused by problems with the inner ear or nerve pathways. Although sound transmission through the outer and middle ear to the inner ear may be normal, the information cannot be coded into electrical signals that the brain can use. People with this type of hearing loss may benefit from an Oticon hearing aid or an Oticon Medical Cochlear Implant System. If you have single-sided deafness, Oticon Medical’s Ponto may also be beneficial.

1. Auditory nerve

2. Inner ear
Conductive hearing loss

Conductive hearing loss is caused by a blockage of sound transmission through the outer ear or middle ear. This can occur due to conditions such as chronic otitis media, otosclerosis (calcification that reduces the mobility of the stapes), malformations of the outer ear or a perforated eardrum.
Conductive hearing loss can be treated in many ways, including using bone anchored hearing systems like Oticon Medical’s Ponto to bypass the middle ear and use vibrations to transmit sounds to the cochlea.

1. Outer ear

2. Middle ear
Mixed hearing loss

Mixed hearing loss is a combination of conductive hearing loss and sensorineural hearing loss. As an example, a chronic infection could cause mixed hearing loss if it damages the eardrum and the ossicles, preventing the cochlea from functioning properly.

Individuals who suffer from this type of hearing loss may also benefit from the use of a bone anchored hearing system like Oticon Medical’s Ponto.

1. Auditory ossicles

2. Eardrum

3. Cochlea