Hearing Loss Severity Classification by Decibel Level
The American College of Medical Genetics and Genomics (ACMG) defines hearing loss severity as: slight (16-25 dB), mild (26-40 dB), moderate (41-55 dB), moderately severe (56-70 dB), severe (71-90 dB), and profound (≥91 dB). 1
Standard Classification System
The ACMG 2022 guideline provides the most authoritative and recent classification framework for categorizing hearing loss by decibel thresholds 1:
- Slight hearing loss: 16-25 dB 1
- Mild hearing loss: 26-40 dB 1
- Moderate hearing loss: 41-55 dB 1
- Moderately severe hearing loss: 56-70 dB 1
- Severe hearing loss: 71-90 dB 1
- Profound hearing loss: 91 dB or greater 1
Alternative Classification Systems
The American Academy of Pediatrics uses a slightly different three-tier system that omits the "slight" and "moderately severe" categories 1:
- Mild: 20-40 dB (functional impact: difficulty with conversations in noisy environments) 1
- Moderate: 40-70 dB (functional impact: difficulty maintaining conversations without hearing aids) 1
- Severe: 70-95 dB (functional impact: requires powerful hearing aids and relies heavily on lip reading) 1
Normal Hearing Threshold
Normal hearing is defined as ≤20 dB HL according to the American Academy of Otolaryngology-Head and Neck Surgery. 2 This threshold represents the upper limit of normal auditory function, with any elevation above this level indicating some degree of hearing impairment 2.
Clinical Context and Functional Impact
The severity classification directly impacts treatment decisions and quality of life outcomes 1:
- Mild to moderate bilateral sensorineural hearing loss (26-55 dB): typically managed with conventional hearing aids 3
- Severe to profound bilateral sensorineural hearing loss (≥71 dB): candidates for cochlear implantation, particularly when diagnosed early 3
- Slight hearing loss (16-25 dB): may go unrecognized but can still impact communication in challenging listening environments 1
Important Clinical Considerations
The classification must be applied to the better-hearing ear to accurately reflect functional hearing status, as this determines the individual's actual communication ability 4, 5. Measurements should be based on pure-tone audiometry at speech frequencies (typically 500,1000,2000, and 4000 Hz averaged) 2.
The ACMG classification system is more granular than older systems, particularly in distinguishing "slight" hearing loss (16-25 dB) and separating "moderately severe" (56-70 dB) from "severe" (71-90 dB), which provides more precise staging for clinical decision-making and genetic counseling 1.