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55 dB vs 85 dB

85 dB is 30 dB louder than 55 dB — about 1000× the sound energy and roughly 8.0× the perceived loudness. In practice that is the difference between a mechanical keyboard and heavy city traffic.

The bars show the two levels on the 0–140 dB scale. The gap looks small as a number, but on a logarithmic scale each 10 dB is a ten-fold jump in energy.

	55 dB	85 dB
Typical source	A mechanical keyboard	Heavy city traffic
Category	Moderate	Very loud
Sound pressure	0.0112 Pa	0.3557 Pa
NIOSH safe time	Unlimited	8 hours
Protection needed	No	Yes

Why 30 dB is a bigger jump than it looks

A 30 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 55 dB to 85 dB therefore multiplies the acoustic energy by about 1000× while your ear reports something closer to 8.0× as loud. Both statements are true — they simply measure different things.

Which one is safe?

55 dB is safe for unlimited exposure, but 85 dB is at or above the 85 dBA action level, where safe time is about 8 hours 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.

Electronic ear muffs (NRR 22–25)Shooting, mowing — amplify speech, block bangsLink coming soon

Reusable filtered earplugs (NRR 20)Concerts & musicians — flat attenuationLink coming soon

Foam earplugs (NRR 32)Sleep, travel, DIY — highest raw NRRLink coming soon

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The distance equivalent

One intuitive way to feel a 30 dB difference is to think in distance. Outdoors, every doubling of distance removes about 6 dB, so standing at 85 dB versus 55 dB is roughly like standing 31.6× closer to the same source. Conversely, moving about 31.6× further away would bring 85 dB down to 55 dB.

Adding the two levels together

Decibels do not add arithmetically. A 55 dB source running alongside a 85 dB source does not produce 140 dB — the correct total is 85.0 dB, calculated as 10 × log₁₀(10^(55/10) + 10^(85/10)). 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 85 dB much louder than 55 dB?

85 dB carries about 1000 times the sound energy of 55 dB and is perceived as roughly 8.00 times as loud.

What is the difference between 55 dB and 85 dB?

The difference is 30 dB. 55 dB is comparable to a mechanical keyboard, while 85 dB is comparable to heavy city traffic.

What do 55 dB and 85 dB add up to?

Combined, two sources at 55 dB and 85 dB produce about 85.0 dB — not 140 dB — because decibels add logarithmically.

Which is safe, 55 dB or 85 dB?

55 dB is below the 85 dBA action level and safe, while 85 dB is at or above it and needs an exposure limit.

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Sources & accuracy. Reference levels are drawn from published data by NIOSH, OSHA, the CDC, the WHO Environmental Noise Guidelines and the American Speech-Language-Hearing Association (ASHA). Real-world readings vary with distance, room acoustics and the specific source, so treat every figure as a typical value rather than an exact constant. Last reviewed 2026-08-11.