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Permissible Noise Level Calculator

Calculate maximum allowable noise levels based on exposure time

Calculation Parameters

Based on ISO 1999, OSHA, and NIOSH standards

Measurement Type

Environment Type

Daily Exposure Time

hours

Distance from Source

Dominant Frequency

Hearing Protection

Regulatory Standard

Calculation Results

Maximum Permissible Level:
—

8-hour TWA Equivalent:
—

Daily Noise Dose:
—

With Protection:
—

Noise Exposure Zones:

Safe: < 80 dBA - No action required

Caution: 80-85 dBA – Hearing protection available

Warning: 85-90 dBA – Hearing protection required

Danger: > 90 dBA – Engineering controls needed

How the Calculator Works

Permissible Exposure Limit

The maximum noise level for a given exposure time:

L_max = L_c + 10 × log₁₀(T_c / T)

where:

L_max — maximum permissible level (dBA)
L_c — criterion level (85 or 90 dBA)
T_c — criterion time (8 hours)
T — actual exposure time (hours)

Time-Weighted Average (TWA)

For varying noise levels throughout the day:

TWA = 10 × log₁₀[1/8 × Σ(t_i × 10^(L_i/10))]

Noise Dose Calculation

Daily noise exposure as percentage:

Dose = 100 × Σ(C_i / T_i)

where C_i is actual exposure time and T_i is allowable time at that level.

Standard Comparison

Standard	Limit	Exchange Rate	Max Level
OSHA	90 dBA	5 dB	140 dB peak
NIOSH	85 dBA	3 dB	140 dB peak
EU	87 dBA	3 dB	140 dB peak

Hearing Protection

Effective protection level calculation:

Effective Level = Noise Level – (NRR – 7) / 2

NRR = Noise Reduction Rating

Distance Attenuation

For point sources in free field:

Each doubling of distance = -6 dB
Indoor environments: -3 to -4 dB per doubling
Near reflecting surfaces: less attenuation

Health Effects by Level

< 70 dBA: No hearing damage risk
70-80 dBA: Possible annoyance
80-85 dBA: Possible hearing damage with long exposure
85-90 dBA: Hearing damage risk, protection required
> 90 dBA: Significant hearing damage risk
> 140 dB: Immediate hearing damage possible

📘 Noise Level Calculator (OSHA/NIOSH)

Determines permissible noise exposure for worker hearing protection. Calculates TWA (Time-Weighted Average) and dose per OSHA/NIOSH standards.

💼 Applications

Workplace Assessment: Pump room: 88 dBA, 8 hours. NIOSH criterion: 85 dBA. Dose: 200%. Mandatory hearing protection (NRR 23 earplugs) → effective 80 dBA ✓
Compressor Room: 94 dBA, operator 2 hours/day. OSHA permissible time: ~4 hours. Dose: 50%. Acceptable without PPE per OSHA, but NIOSH requires protection.
Combined Exposure: 3h at 90 dBA + 3h at 82 dBA + 2h at 95 dBA. TWA = 88.5 dBA. Dose: 67%. Wear protection at pneumatic tools.

Key Standards:

OSHA: 90 dBA for 8h, 5 dB exchange rate, max 140 dB peak

NIOSH: 85 dBA for 8h, 3 dB exchange rate (more conservative)

NRR Derating: Effective reduction = (NRR – 7) / 2

Permissible Noise Level Calculator | Vibromera.eu

Published by admin on October 20, 2025 October 20, 2025

Calculation Parameters

Calculation Results

Noise Exposure Zones:

How the Calculator Works

Permissible Exposure Limit

Time-Weighted Average (TWA)

Noise Dose Calculation

Standard Comparison

Hearing Protection

Distance Attenuation

Health Effects by Level

📘 Noise Level Calculator (OSHA/NIOSH)

💼 Applications

Key Standards: