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Types of hearing loss
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Classification of hearing loss: |
Hearing deficit is classified according to quantitative (the audiometric assessment provides the degree of deafness), qualitative or topodiagnostic (defining the seat of damage) and chronological criteria. The latter refer to the period in which the damage arose.
According to the BIAP (Bureau International d'Audiophonologie) the average total hearing loss is calculated considering the frequencies 500, 1000, 2000, 4000 Hz, And the sum of hearing loss in dB of the frequencies considered is divided by four in order to calculate the average loss. According to these criteria, the following are considered:
- Normal hearing (auditory threshold below 20 dB)
- Mild deafness (auditory threshold between 20 and 30 dB)
- Medium deafness (threshold between 30 and 60 dB)
- Serious deafness (auditory threshold between 60 and 90 dB)
- Profound deafness above 90 dB
According to the seat of the lesion, hypoacusis is divided into:
- Transmissive or by conduction
- Neurosensory or perceptive
- Mixed
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