What to Expect from a Hearing Test – Pure Tone Audiometry A.K.A ‘The Beep Test’Penelope Woods
The Beep Test
When you think of a hearing test you most likely think of the ‘beep test’; listening carefully through a pair of headphones for different notes to be played at different volumes. In this blog, I’ll explain what happens during this part of the hearing test, and why we do it.
At a Glance
- Beep noises are played through earphones, and through a headband, at different frequencies and volumes to test your hearing sensitivity.
- A quiet, sound-treated, space is required for reliable results.
- Some beeps will be very hard to hear – that’s normal. Those are at the limit of your hearing.
What to expect during a hearing Beep Test
A beep test should be performed in a soundproof booth or similarly sound-treated room. Headphones will probably be applied to your ears and should fit snuggly but comfortably. For adults however, it is considered best clinical practice to use ‘insert earphones’ – these are small foam-covered earphones which sit inside the ear canal. This is to ensure the test sound is delivered deeply into the canal. Ear canals can narrow with age or be squished by regular headphones. If this happens you may not hear high beeps as well as you ordinarily would, which could result in a false test result.
The test will take around 10 minutes and will consist of a range of pure tones (or ‘beeps’) played through the earphones. You will be asked to press a button when you hear a beep. This indicates to the clinician that your hearing is working at that specific frequency and at that specific volume.
The clinician will continue playing a variety of beeps at different frequencies (think; different notes on a piano keyboard) and at different volumes to get a comprehensive and reliable test result.
Air Conduction and Bone Conduction
Earphones are used to measure how sensitive your hearing is via Air Condition, (i.e. as the sound travels through your outer ear, middle ear and into your inner ear or cochlea; the organ of hearing). This forms only the first part of the beep test as it only tells us whether there is a hearing loss – it doesn’t tell us which part of the ear is responsible for the loss. To find that out, you need to complete a Bone Conduction test.
To perform a Bone Conduction test, a tight-fitting headband (bone conductor) is placed diagonally across your head to deliver the different beeps directly to your cochlea via sound vibrations. Again, you will be asked to respond when you hear a beep. The results from this test will be compared to the results from the earphones, to see if there is a fault with the middle ear, the cochlea, or both.
It is best practice to perform the two different types of beep testing as they directly impact the clinical pathway recommended. For example, should you be referred to an Ear Nose and Throat specialist for medical treatment or do you need hearing rehabilitation?
Red Flags and Warning Signs
Firstly, pay attention to the headphones used in your test. They should be insert earphones like those described above.
Secondly, if a beep test is performed in an environment where background noise is present it will not be as reliable as if it was performed in a test booth or sound treated room. This is because background noise can supress the quietest beeps resulting in a worse test result. An inaccurate result could lead to an incorrect or more expensive recommendation.
Thirdly, it’s not uncommon from the Bone Conduction test to be skipped altogether but both Air Conduction (earphone) and Bone Conduction (headband) testing should be performed during an audiological assessment to determine the site of the hearing loss.
Fourth and finally, patients should check the scale of the graph displaying your results.
Below is an example of what a graph, or audiogram, should look like (figure 1.). The intervals on the left-hand side are evenly spaced, and the measurements start at -10dB (dB = decibels). This is incredibly quiet. Measurements then go down by 10dB intervals. Healthy human hearing should not fall below 20dB (indicated by the 20 on the left-hand margin). We call this ‘hearing within normal limits’. A test result appearing below the 90dB marker is considered ‘profoundly deaf’.
The audiogram displays the test results in red and blue. The colours indicate Right ear (red circles) and Left ear (blue crosses). In this example the patient has a mild hearing loss in the high registers (notice how the results dip on the right of the graph between 4k and 8k). The loss is considered mild. It is not ‘clinically indicated’ that this person needs hearing aids.
Imagine the impact of viewing your results on a graph such as the one in Figure 2. In this case, the hearing results are the same as in Figure 1. but because the dimensions of the graph have been altered, the hearing loss appears more dramatic. Compare the differences in scale on the left margin.
Expect your results to be displayed on an audiogram which obeys the clinical standard displayed in Figure 1. (I.e.; -10dB to 120dB on the left-hand margin and 125(Hz) to 8 kHz along the top). In some cases, diagnostic testing above 8 kHz may be warranted, however we normally only need to test up to 8 kHz.
When performed correctly and viewed in summary, otoscopy, tympanometry, and pure tone beep tests (including both Air Conduction and Bone Conduction), provide a wealth of information about the hearing system. However, they don’t give us the complete picture.
If they were all that was required, many more hearing aid users would be satisfied with their hearing aids restaurants, shopping centres and cafés. As you may know these busy environments are particularly challenging for hearing aid users and non-users alike.
To understand what is going on in these more challenging environments, we need to understand the brains role in hearing. That means performing ‘speech’ and ‘speech in noise’ testing, which we’ll look at in the next post.