Types of Hearing loss : A. Degree and B. Shape
A. Degree of hearing loss refers to the severity of the loss. The table below shows one of the more commonly used classification systems. The numbers are representative of the patient's hearing loss range in decibels (dB HL).
Degree of hearing loss Hearing loss range (dB HL)
Normal –10 to 20
Mild 20 to 40
Moderate 40 to 70
Severe 70 to 90
Profound 90 to 120
B. The shape, of the hearing loss refers to the degree and pattern of hearing loss across frequencies (tones), as illustrated in a graph called an audiogram. For example, a hearing loss that only affects the high tones would be described as a high-frequency loss. Its configuration would show good hearing in the low tones and poor hearing in the high tones.
1. Normal
2. High Frequency hearing loss - Ski Slope
3. Low Frequency Hearing Loss - Reverse Ski Slope
4. Low, Mid and High Frequency Hearing Loss - Flat
5. Mid Range Frequency Loss - Cookie Bite
6. Low and High Frequency Loss - Reverse Cookie Bite
Bilateral versus unilateral. Bilateral means hearing loss in both ears. Unilateral means hearing loss in one ear.
Symmetrical versus asymmetrical. Symmetrical means the degree and configuration of hearing loss are the same in each ear. Asymmetrical means degree and configuration of hearing loss are different in each ear.