How Hearing Tests Measure Different Sound Frequencies

A hearing test is not a yes or no test of whether you can hear or not. It’s a test to find out how you hear different sounds or pitches.

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What the Frequency Range Covers

The test usually covers the frequency range from 250 Hz up to 8,000 Hz. The low frequencies have the most power in vowel sounds, while the higher frequencies have the most power in the consonants such as ‘s’, ‘f’ and ‘th’ that add detail to speech and make it clear rather than just audible.

How Thresholds Are Found

Pure-tone audiometry is used to determine the threshold (quietest level at which a person can just about hear) for different frequencies. The result is then plotted on an audiogram to give a graph, which highlights areas of hearing within normal limits and where any hearing loss exists.

Which Frequencies Go First

For many people high frequency hearing loss starts at around 4,000Hz. This type of loss is very often as a result of prolonged exposure to loud noise, but age can also be a causative factor. A person with this type of loss may find they can hear a loud conversation but the speech fails to be clear. This is because the consonants are in the high frequency range and therefore not heard as well as the vowels in the low frequency range which are carrying the power of the sound.

How the Audiogram Maps the Results

Each threshold is plotted on an audiogram (a graph) and these are plotted with frequency on the top of the graph and volume on the side of the graph. The resulting ‘graph’ of the hearing test results shows a straight line across for someone with normal hearing, and where there is a drop in hearing this will show up as a dip in the line for specific frequencies. From this pattern a number of things can be ascertained i.e. the degree of hearing loss, and possible causes of the hearing loss.

What a Drop at One Frequency Tells the Audiologist

The same principle applies when looking at an audiogram. A sharp drop at 4,000 Hz indicates that the individual has suffered noise damage to their hearing, whereas a gradual fall across the high frequency range (2,000-8,000Hz) is typical of age-related hearing loss. The audiogram pattern will lead the clinician to apply the appropriate treatment for the individual’s hearing loss. A useful reference for Hearing Test Bristol is www.imperialhearing.com/audiologist-near-me/bristol/.

The frequency-by-frequency picture is far more informative than a single pass/fail score for hearing ability.