50 dB vs 120 dB
| 50 dB | 120 dB | |
|---|---|---|
| Typical source | Moderate rainfall | An ambulance siren at 1 m |
| Category | Moderate | Dangerous |
| Sound pressure | 6.3e-3 Pa | 20.0000 Pa |
| NIOSH safe time | Unlimited | 8.9 sec |
| Protection needed | No | Yes |
Why 70 dB is a bigger jump than it looks
A 70 dB gap looks small written down, but decibels are logarithmic. Every 10 dB multiplies sound energy by ten and roughly doubles perceived loudness. Going from 50 dB to 120 dB therefore multiplies the acoustic energy by about 10000000× while your ear reports something closer to 128.0× as loud. Both statements are true — they simply measure different things.
Which one is safe?
50 dB is safe for unlimited exposure, but 120 dB is at or above the 85 dBA action level, where safe time is about 8.9 sec without protection.
Hearing protection
For anything above 85 dB, rated protection matters. Look at the NRR (US) or SNR (EU) figure — real-world reduction is roughly (NRR − 7) ÷ 2.
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The distance equivalent
One intuitive way to feel a 70 dB difference is to think in distance. Outdoors, every doubling of distance removes about 6 dB, so standing at 120 dB versus 50 dB is roughly like standing 3162.3× closer to the same source. Conversely, moving about 3162.3× further away would bring 120 dB down to 50 dB.
Adding the two levels together
Decibels do not add arithmetically. A 50 dB source running alongside a 120 dB source does not produce 170 dB — the correct total is 120.0 dB, calculated as 10 × log₁₀(10^(50/10) + 10^(120/10)). Because the louder source dominates, the quieter one contributes only 0.0 dB. Our decibel calculator does this for any combination.
Frequently asked questions
Is 120 dB much louder than 50 dB?
What is the difference between 50 dB and 120 dB?
What do 50 dB and 120 dB add up to?
Which is safe, 50 dB or 120 dB?
See each level in detail
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