Noise dose
Used on the ASP, CSP and CHST. The worked example below is computed by code and checked against the source.
D = 100 × (C1/T1 + C2/T2 + … + Cn/Tn)
C = hours at a given sound level; T = OSHA reference duration for that level from Table G-16a (90 dBA = 8 h, 95 dBA = 4 h).
Worked example
4 h at 90 dBA and 4 h at 95 dBA.
100 × (4/8 + 4/4) = 150%
Run your own numbers: noise dose calculator or decibel addition calculator.
Where it appears on the exam
ASP: ASP11 Domain 1, Mathematical Calculations
Blueprint: ASP11 Domain 1, task 5: noise hazards (TWA)
Practice: Occupational Noise and Hearing Conservation, Safety Math: Incident Rates, Noise Dose, Slopes, Lifting
CSP: CSP11 Domain 6, Occupational Health and Applied Science
Blueprint: CSP11 Domain 6, task 1: occupational exposures (noise)
Practice: Exposure, Noise, Containment and Lifting Calculations, Occupational Noise
CHST: CHST5 Domain 1, Hazard and Risk Identification and Control
Blueprint: CHST5 Domain 1, knowledge 18: noise exposure
Practice: Construction Safety Math: Noise and Excavation Slopes, Noise, Hearing Protection, Radiation and Lasers
Source
The formula comes from
29 CFR 1910.95, Appendix A(opens ecfr.gov in a new tab)“When the workshift noise exposure is composed of two or more periods of noise at different levels, the total noise dose over the work day is given by: D = 100(C1 / T1 + C2 / T2 + Cn / Tn), where Cn indicates the total time of exposure at a specific noise level, and Tn indicates the reference duration for that level as given by Table G-16a.”
Questions
- What is the formula for noise dose?
- D = 100 × (C1/T1 + C2/T2 + … + Cn/Tn). C = hours at a given sound level; T = OSHA reference duration for that level from Table G-16a (90 dBA = 8 h, 95 dBA = 4 h).
- Will this formula be given on the BCSP exam?
- BCSP says the formula is included in the question whenever one is needed, unless the question is testing whether you know the formula. You can't bring a formula sheet into the exam, so learn what each formula does and when to use it.
BCSP on formulas at the exam
BCSP, What to Expect When Sitting for a BCSP Exam (item 7)(opens bcsp.org in a new tab)“For any question requiring a mathematical formula, the formula will be included within the exam question (unless the question is specifically testing your knowledge of a formula). You will not be provided or permitted to bring a formula sheet.”
Related
- Action level
- Noise TWA from dose
- Reference duration for a sound level
- Adding decibels
- Sound level at a distance
- Hearing protector NRR (estimated exposure)
- ASP formula sheet
- CSP formula sheet
- CHST formula sheet
Checked 2026-10-16. Spot a problem? Email hello@passcited.com.