Audiometric Testing Explained

Audiometric testing is used to assess a patient’s ability to hear sound. This type of examination can be used both to test hearing loss and ensure a hearing aid is working properly. If you’re concerned about your hearing and are about to go for an audiometric test, take a look at our guide to find out exactly what to expect.

 

Types of Audiometric Testing

Hearing tests can take a number of different forms. Basic audiology tests can be carried out in a doctor’s office and may involve completing a questionnaire and listening to whispered voices, tuning forks or tones from an ear examination scope. This type of test will indicate if there is hearing loss, however, it won’t define the type of hearing loss the patient is experiencing or provide the audiologist with detailed information. 

If an audiologist suspects more serious hearing issues, they may carry out a formal hearing test. This will thoroughly examine the patient’s hearing ability and determine their degree of hearing loss. 

There are a number of different tests that can be carried out. These include:

• Pure tone testing
• Bone conduction testing
• Speech testing
• Tympanometry
• Immittance audiometry
• Acoustic reflex testing
• Auditory brainstem response
• Otoacoustic emissions
• Pitch matching test

Pure Tone Testing

Pure tone testing, also known as pure tone audiometry, uses air conduction to measure a patient’s ability to hear sounds at various pitches and volumes. During a pure tone test, the patient will sit in a specially designed booth and will listen to a series of sounds via earphones.

The patient will be asked to make a signal – such as raising their hand or pressing a button – every time they hear a sound. The minimum volume required to hear each tone is graphed by an audiometer and the test results charted on an audiogram. 

Bone Conduction Testing

Bone conduction testing is another type of pure-tone testing. It measures the response of a patient’s inner ear to sound. During the test, a conductor will be placed behind the patient’s ear, against the mastoid bone, and will send tiny vibrations through the bone directly to the inner ear. This is designed to test bone conduction, an important aspect of hearing.

Speech Testing

Also known as a word recognition test, speech discrimination test or speech audiometry, speech testing measures the patient’s ability to detect and repeat spoken sounds. This type of testing is used to measure the speech reception threshold (SRT), which indicates the faintest speech that can be understood 50% of the time. It also measures the patient’s ability to separate speech from background noise. The test can be administered in either a quiet or noisy environment.

Tympanometry

Tympanometry measures the movement of the eardrum (tympanic membrane) in response to air pressure. The test can determine if there’s a build-up of fluid or wax, eardrum perforations or a tumor like an acoustic neuroma.

Immittance Audiometry

Immittance audiometry measures the function of the eardrum and the flow of sound through the middle ear. During the test, a probe is inserted into the ear and air pumped through it to change the pressure as tones are produced. During the test, a microphone is used to monitor how well sound is conducted within the ear under different pressures.

Acoustic Reflex Testing

Acoustic reflex testing is used to measure the involuntary muscle contractions of the middle ear. This can help audiologists to determine the location of a hearing issue, for example, in the ossicles, cochlea or auditory nerve. It can also indicate the type of hearing loss the patient is experiencing.

Auditory Brainstem Response

Auditory brainstem response (ABR) is commonly used to screen newborns for hearing problems. ABR can also determine if a patient has sensorineural hearing loss. During this type of audiometric testing, electrodes are attached to the head, scalp or earlobes and the patient is given earphones to wear. Brainwave activity is measured in response to sounds of varying intensities.

Otoacoustic Emissions

Otoacoustic emissions are sounds generated by the vibrations of the hair cells in the cochlea of the inner ear. They can be tested by placing a tiny probe, fitted with a microphone and speaker, into the ear to stimulate the cochlea. People with normal hearing will produce emissions. However, when hearing loss exceeds 25-30 decibels, no sound will be produced.

Otoacoustic emissions testing helps audiologists to determine whether there is a blockage in the ear canal, excess fluid in the middle ear or damage to the hair cells of the cochlea. 

Pitch Matching Test

Pitch matching tests allow audiologists to check for tinnitus. During the test, the audiologist will play several different high frequency tones into the patient’s earphones. When they find the one that matches their tinnitus, they can indicate it by raising a hand or pressing a button.  

 

How a Hearing Test Works

The loudness, or volume, of sound is measured in decibels (dB). A whisper is about 20 dB, while a very loud noise, like a jet engine, is about 180 dB. The tone of sound is dictated by its frequency which is measured in Hertz (Hz). Low bass tones range from 50 to 60 Hz and high-pitched tones are generally 10,000 Hz or higher. Normal hearing range is 20-20,000 Hz. Most people can hear sounds of 10 dB and higher.

Hearing tests are used to determine if a person’s hearing level falls outside of this normal range. If it does, the patient may experience some amount of deafness and could require a hearing aid. 

Different hearing tests are used to measure different types of hearing loss. Our ears have three distinct areas – the outer ear, middle ear and inner ear – and each plays a role in transmitting sound from outside to in. Audiologists use various hearing tests to find out exactly where the issue is and learn more about what could be causing it.

The three main types of hearing loss these tests measure are: 

• Sensorineural hearing loss - damage to the nerve or cochlea
• Conductive hearing loss - damage to the eardrum or the tiny ossicle bones
• Age-related hearing loss – a type of sensorineural hearing loss that gets worse as a person ages

In some cases, a person may have asymmetrical hearing loss, with either the left ear or right ear more affected. 

Auditory tests are incredibly useful when it comes to measuring a patient’s hearing threshold and assessing hearing loss. Find out more, and learn about the high quality audiology equipment in our collection, by taking a look around today.