Degrees of Hearing Loss

A classification system for degrees of hearing loss, based on threshold hearing levels.

The degree of hearing loss a person has can be characterized by how loud a sound has to be in order for the person to be able to hear it. For a person with normal, healthy hearing, the faintest sound that can be heard is 0 decibels, but for someone with a hearing loss, a sound must be louder than 0 dB before it can be heard. A hearing test can measure the softest sound that the person can detect. The higher a person's hearing threshold, the higher the degree of hearing loss that person has.

When measuring a person's hearing level, a range of frequencies (pitches) are used, and the hearing threshold at each frequency will be determined for each ear. The resulting audiogram gives a detailed view of the nature of the hearing loss, which is essential in order to know what treatments may help. To arrive at a single number that is used as the overall threshold hearing level, only the better ear is used, and the threshold levels for that ear are averaged across the frequencies tested.

Knowing the person's overall threshold hearing level from the hearing test results, we can classify the degree of hearing loss, from slight to profound. There is no standard classification system that is universally used, but one system commonly used is the one recognized by the Hearing Loss Association of America:

Degree of Hearing LossThreshold Hearing Level (dB HL)Effect on CommunicationUse of Hearing Aids
Normal−10–15no hearing impairment 
Slight16–25speech understanding not affected 
Mild 26–40speech understanding reduced, especially in noisy environmentsmay be helpful
Moderate41–55conversation noticeably difficulthighly beneficial; strongly recommended
Moderately severe56–70speakers must raise their voice to be heardessential
Severe71–90conversational speech cannot be heardof less benefit
Profound91 or higherdeafof little benefit; cochlear implants may be considered

For reference, note that conversational speech is around 60 dB.

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Sarinne Fox
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