Why Is Pure Tone Audiometry a Common Hearing Test?
Often used as a first-line diagnostic assessment, a pure tone audiometry test enables hearing care professionals to determine whether a patient is experiencing hearing loss. However, a pure tone audiometry hearing test doesn’t only confirm or rebut a potential diagnosis; it highlights the severity, type and configuration of hearing loss too.
What is pure tone audiometry?
As the name suggests, this type of hearing test uses pure tones at different frequencies to measure hearing acuity. By playing pure tones at varying frequencies and monitoring the participant’s response, a hearing care professional can determine whether hearing loss is present.
During a pure tone hearing test, a sound at a particular frequency may be played repeatedly at different volumes. The hearing care professional (HCP) will monitor when the participant is no longer able to hear the sound. This reveals at what decibel that particular frequency becomes inaudible for the participant.
Following this, sounds are played at a different frequency and the process is repeated. This allows the HCP to build up a picture of the individual’s hearing sensitivity. A chart, known as an audiogram, is used to plot the points at which the participant is no longer able to hear the sounds being played.
Once the audiometry test is complete, the audiogram shows the participant’s hearing function across a range of frequencies and decibels. This enables the HCP to compare the individual’s results with commonly accepted hearing norms to determine whether hearing loss is present. Furthermore, a hearing care professional can use the results plotted on the audiogram to determine what frequencies are affected and to what degree.
Why is pure tone audiometry a common hearing test?
Pure tone audiometry is a standard hearing test for a variety of reasons, including:
Generally considered the be the ‘gold standard’ of hearing function tests, pure tone audiometry tests deliver highly accurate results. Due to this, they are the preferred test amongst the majority of hearing care professionals.
Amount of data produced
When assessing a patient, pure tone tests are carried out on each ear. This enables the HCP to assess individual hearing loss. As well as identifying a loss of hearing function in one or both ears, a pure tone audiometry test highlights the type of hearing loss and the severity of hearing loss.
Pure tone audiometry hearing tests can be carried out relatively quickly. Most tests can be completed in around 20-30 minutes. This means audiologists can comprehensively test a number of patients within a short timeframe.
What are the advantages of pure tone audiometry hearing tests?
As well as being extremely accurate and a fast way to assess hearing function, there are a range of additional benefits associated with pure tone audiometry testing. These include:
The range of information available following an audiometry hearing test is extremely valuable to audiologists and hearing care professionals. In many cases, patients will not require additional hearing function tests and can access appropriate treatment and symptom management following one non-invasive standard hearing test.
Minimal equipment required
To carry out pure tone audiometry testing, HCPs simply need to provide a quiet environment, headphones, a recording of appropriate sounds and audiograms to record the results.
As minimal equipment is required to conduct pure tone audiometry testing, they are a relatively low-cost way to assess an individual’s hearing function. Despite this, they provide a wide range of data and offer highly accurate results.
What other options are there to assess hearing function?
Although audiometry tests are often used to diagnose and assess hearing function, alternative or additional tests may be used in some circumstances, such as:
Bone conduction tests
A bone conduction test bypasses the outer and middle ear and uses vibration to send sounds directly to the inner ear. Bone conduction tests can be used when something is blocking the outer or middle ear or to identify specific types of hearing loss, particularly when used in conjunction with pure tone audiometry tests.
Used to assess middle ear function, tympanometry involves using varying degrees of air pressure to assess the mobility of the tympanic membrane (eardrum) and conduction bones.
Routinely used to determine how well the participant can differentiate speech in different environments. By evaluating the faintest speech an individual can hear at least 50% of the time, their speech recognition threshold (SRT) can be determined.
Auditory brainstem response (ABR)
Audiologists typically use ABR testing to determine whether sensorineural hearing loss is present. The individual’s brain waves are monitored to confirm whether activity occurs in response to sound.
Acoustic reflex testing
When normal hearing function is present, the stapedial muscle stiffens in response to loud sounds. By monitoring the stapedial reflex, hearing care professionals can assess some elements of hearing function.
Otoacoustic emissions (OAEs)
When OAE testing is performed, the cochlea is stimulated to assess its response. When no OAEs are produced, it indicates that hearing loss exceeding 25-30 decibels is present. OAE testing may be used to determine whether excess fluid is present in the middle ear, a blockage in the ear canal exists or whether the hair cells of the cochlea have been subject to damage.
Comprehensive Testing for Hearing Loss
Audiometric evaluation can take place in a number of ways. While a suite of hearing function tests may be used to diagnose complex hearing issues or congenital hearing loss, fewer tests are typically required to diagnose and assess hearing loss in the majority of individuals.
Due to the variety of data produced via pure tone audiometry testing, as well as the minimal amount of equipment required, the low cost and the non-invasive nature of the test, it remains the ‘gold standard’ of audiometry testing and is generally the first-line diagnostic hearing test to be used.