NR curva aprox de dB
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The Noise Rating (NR) calculator converts A-weighted decibel (dB(A)) measurements into standardized noise classifications using the simplified formula: (dB(A) − 10) / 5 × 5. This calculation adjusts sound levels to a rating scale commonly used in acoustic studies and industrial noise assessments. The formula reduces the measurement by 10 dB and aligns it with 5-dB increments for easier comparison against safety standards.
This tool is useful for projects involving environmental or industrial noise analysis. For instance, engineers and occupational health professionals use this method to verify compliance with legal noise limits. The formula replaces complex tables with a quick approximation based on standardized rules for NR curves.
Before using it, ensure the input is in dB(A), not other weighting scales (e.g., C or Z). Note that this formula is specific to NR curves and may not apply to other noise rating systems like PNC or NR-20. Always cross-check with local regulations to validate results.
Frequently asked questions
What is the difference between dB(A) and NR?
dB(A) measures sound levels weighted to human hearing perception, while NR is a simplified classification derived from dB(A) for environmental noise standards.
Why subtract 10 dB in the calculation?
Subtracting 10 dB is part of the standard formula to align dB(A) with the linear NR scale for easier interpretation.
Can I use this calculator for other noise ratings?
No, this tool is designed for NR curves. For other ratings (like PNC), refer to specific standards.
What if my measurement isn't in dB(A)?
Convert the value to dB(A) first using appropriate tools before using this calculator.