Degree of hearing loss is computed by using a three frequency average. The degree of loss in dB HTL is taken at 500 Hz, 1,000 Hz and 2,000 Hz. The average of these three frequencies is called the Pure Tone Average or PTA and is the degree of hearing loss a person has expressed in dB.
The following chart relates the degree of loss to a hearing loss classification.
| Hearing Loss Table | |
| PTA | Classification |
| 0-20 dB | Normal |
| 21-40 dB | Mild Loss |
| 41-60 dB | Moderate Loss |
| 61-70 dB | Moderately Severe |
| 71-90 dB | Severe Loss |
| > 90 dB | Profound Loss |