Understanding Hearing Loss

Degree of Hearing Loss

Sound is measured in decibels (dB) with normal conversational voice around 60dB.  A hearing test measures the quietest sounds that can be heard (hearing threshold) at different frequencies. The frequencies tested range from low frequencies sounds (125Hz) to high frequency sounds (8000Hz), similar to the low notes and high notes on a piano. This information is recorded on a graph called an audiogram, shown below.

The British Society of Audiology (2018- 27) uses four audiometric descriptors to categorise the degree of hearing loss.

Descriptor                         Average hearing threshold levels (dBHL)

Mild hearing loss              21 - 40

Moderate hearing loss     41- 70

Severe hearing loss         71-95

Profound hearing loss      In excess of 95

Terminology

Bilateral hearing loss - both ears

Unilateral hearing loss - one ear only

Congenital hearing loss - present at or before birth

Flat loss - hearing thresholds are the same in the mid, low and high frequencies.

Ski-slope hearing loss - worse in the high frequencies

Reverse-slope hearing loss - worse in the low frequencies

Cookie-bite hearing loss - mid frequency loss, with a u shaped audiogram

Progressive hearing loss - deteriorates over time.

Understanding the shape of the line on the audiogram, helps you to understand the different kinds of hearing loss.

Reference

British Society of Audiology (2018) Recommended Procedure Pure-tone air-conduction threshold audiometry with and without masking. [Online] Available at: https://www.thebsa.org.uk/resources/pure-tone-air-bone-conduction-threshold-audiometry-without-masking/   [Accessed 13 February 2021]