5.4 HSE Hearing Surveillance Categorisation (Categories 1-4)
Audiometry
• Category 1 (Acceptable): Hearing within normal range. Continue routine surveillance (e.g., every 3 years).
• Category 2 (Warning): Mild impairment detected. Warn employee, check PPE fit, retrain on protection use, increase test frequency.
• Category 3 (Referral): Significant hearing loss. Refer to Occupational Health Professional (OHP) for medical assessment.
• Category 4 (Rapid Loss): ≥30 dB deterioration in ≤3 years. Immediate OHP referral, consider removal from noise exposure.
HSE Hearing Surveillance Categorisation
What it is: The HSE categorisation scheme for audiometry is the standard protocol for managing health surveillance under the Control of Noise at Work Regulations 2005. It classifies workers into four categories based on the sum of their hearing threshold levels at 1, 2, 3, 4, and 6 kHz, compared against age- and sex-standardised data (based on ISO 7029). The primary source for this scheme is L108 Appendix 5.
Category 1: Acceptable Hearing Ability
• Hearing levels within normal range for age and sex
• Sum of hearing levels below the Warning Level (20th percentile)
• Action: Inform employee, record result, continue routine surveillance (e.g., every 3 years)
• No medical referral required
Category 2: Mild Hearing Impairment (Warning)
• Hearing worse than average for age, indicating potential susceptibility or early NIHL
• Sum between Warning Level and Referral Level (5th percentile)
• Action: Warn employee; check fit and condition of hearing protection; retrain on correct use; review risk assessment
• More frequent testing recommended (e.g., annually)
Category 3: Poor Hearing (Referral)
• Significant hearing impairment present
• Sum exceeds Referral Level (worse than 5th percentile)
• Action: Review noise exposure and controls immediately; ensure strict PPE adherence
• Medical Referral Required: Refer to Occupational Health Professional (OHP) to determine cause and fitness for continued work in noisy environments
Category 4: Rapid Hearing Loss
• Deterioration of ≥30 dB in sum of hearing levels over ≤3 years
• Indicates current controls are failing or individual is highly susceptible
• Action: Consider immediate removal from noise exposure; conduct urgent review of risk controls and PPE suitability
• Immediate Medical Referral Required: Employee must be seen by OHP to investigate rapid decline
Important Note on Referrals (Post-2021): Current HSE guidance emphasises managing referrals through Occupational Health services rather than overburdening GPs. The OHP should triage results—GP referral is only necessary if a medical condition requiring treatment is identified (e.g., acoustic neuroma, infection). For NIHL alone, management is a workplace safety issue.
Why it matters: This categorisation scheme provides a standardised framework for interpreting audiometric results and determining appropriate employer responses. It ensures consistency in health surveillance programmes and helps employers meet their obligations under Regulation 9 of the Control of Noise at Work Regulations 2005.
Related: 1.7 Health Surveillance (Regulation 9), 1.7.1 Health Records, 2.1 L108 Guidance
Quick Reference: Actions by Category
Category | Status | Employer Action | Re-test |
1 | Acceptable | Inform employee; record result | 3 years |
2 | Warning | Warn employee; check PPE; retrain | Annual |
3 | Referral | Refer to OHP; review controls | As advised |
4 | Rapid Loss | Immediate OHP referral; consider removal | As advised |