Hearing tests

Hearing tests check a person’s ability to hear sounds of different loudness and pitch. The results are charted on a graph called an audiogram, which helps pinpoint the severity and cause of any hearing problems. Tests include pure tone audiometry, using an audiometer, and speech discrimination tests. Special tests are also available to check hearing in babies and children. These tests are usually carried out by hearing specialists called audiologists.

How we hear#

A sound wave is made up of vibrating air molecules. Gentle vibrations make a soft sound, while large vibrations make a loud one. The loudness of a sound is measured in decibels (dB). A sound’s pitch, or frequency, is the number of vibrations per second, measured in hertz (Hz). Slow vibrations make a low-frequency sound (such as a foghorn), while rapid vibrations make a high-frequency sound (such as a whistle).

Signs you may need a hearing test#

Some signs that your hearing should be checked include:

• A ringing sensation in the ears (tinnitus)
• People complain that you talk too loudly
• You often have to ask people to repeat what they say
• You find it hard to follow conversations, especially with background noise
• Others say you watch television with the volume turned up too high

A range of hearing tests#

There are several types of hearing test, including:

• Pure tone audiometry: a machine called an audiometer produces a range of beeps and whistles (pure tones), and you press a button or otherwise indicate when you hear them. Listening through headphones tests your air conduction hearing, which checks the outer hearing pathway as well as the inner ear. Listening through a bone conductor (a vibrator held against the mastoid bone behind the ear) measures what your inner hearing pathways can detect.
• Speech discrimination tests: a test of how clearly you hear speech, in which you repeat words said to you.
• Online hearing screening: wearing headphones, people can check their hearing in background noise. These short tests can give an indication of hearing ability but are not a substitute for a full assessment.

Age-related hearing loss (presbycusis) typically begins with the loss of higher frequencies, so that certain speech sounds (such as “p”, “f” and “t”) start to sound very similar.

Hearing tests for babies and children#

Some babies are at increased risk of hearing problems. Risk factors include premature birth, low birth weight and jaundice. The type of test used depends on the age of the child and can include:

• Objective tests, such as otoacoustic emission testing, auditory brainstem response testing, electrocochleography and tympanometry. These do not require a response from the child and give the most accurate indication of hearing ability in most babies under about six months of age.
• Behavioural observation audiometry (BOA): for younger babies, this involves making noises, such as shaking a rattle nearby, and observing the baby’s response.
• Visual reinforcement orientation audiometry: the baby is taught to turn towards a sound by pairing it with an interesting visual reward, such as a puppet. Their response to different sounds can then be measured, and the ears can be tested individually if the baby will tolerate headphones.
• Play audiometry: older children are taught to respond to sounds by playing a game, such as dropping a marble each time they hear a sound.

Objective hearing tests#

Objective tests measure the response of the ear and hearing pathways without needing the person to respond. They include:

• Otoacoustic emission testing: checks the function of the tiny hairs in the cochlea. The faint sound the hairs make in response to sound is called the otoacoustic emission.
• Auditory brainstem response testing: checks the electrical activity in the brain in response to sound, using electrodes placed on the head to measure brain waves.
• Electrocochleography: checks the cochlea for electrical activity in response to sound, using an electrode placed against the cochlea.
• Tympanometry: a rubber tip is placed in the ear and air is gently pumped into the ear canal. This is not a hearing test but checks whether the eardrum moves normally.

The audiogram explained#

The audiologist charts the results of your tests on a graph called an audiogram. The results usually include your hearing threshold (the softest sounds you can hear) across a range of frequencies for both ears. By comparing these figures, the audiologist can assess the degree of hearing loss and find clues to its cause. For example, if the air and bone conduction results are the same, the hearing loss is coming from the inner ear rather than the outer or middle ear.

Types of hearing loss#

Hearing tests can distinguish the type of hearing loss, including:

• Conductive: a sound blockage in the middle or outer ear (or both), usually caused by middle ear infections or by a build-up of wax in the ear canal.
• Sensorineural: the cochlea or cochlear nerve is damaged.
• Mixed: a combination of conductive and sensorineural problems.

Hearing loss can also be described by when it occurs:

• Congenital: the loss is present before or just after birth. Exposure to certain diseases in the womb or soon after birth can harm a baby’s hearing.
• Acquired: the loss happens later in life, for example through disease or trauma.

Severity of hearing loss#

Hearing loss is measured in decibels (dB). Conversational speech is around 65 dB. The degrees of hearing loss include:

• Mild (21–45 dB): soft sounds may be difficult to distinguish.
• Moderate (46–60 dB): conversational speech is hard to hear, especially with background noise such as a television or radio.
• Moderately severe (61–75 dB): it is very difficult to hear ordinary speech.
• Severe (76–90 dB): conversational speech cannot be heard.
• Profound (91 dB and above): almost all sounds are inaudible.

Most people with profound hearing loss benefit from a hearing aid.

Key points#

• Hearing test results are charted on a graph (audiogram) to help pinpoint the severity and cause of hearing problems.
• Some babies are at increased risk of hearing problems.
• Risk factors include premature birth, low birth weight and jaundice.

Where to get help#