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70 dB vs 90 dB

90 dB is 20 dB louder than 70 dB — about 100× the sound energy and roughly 4.0× the perceived loudness. In practice that is the difference between a vacuum cleaner at 3 m and a petrol lawn mower.

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.

	70 dB	90 dB
Typical source	A vacuum cleaner at 3 m	A petrol lawn mower
Category	Loud	Very loud
Sound pressure	0.0632 Pa	0.6325 Pa
NIOSH safe time	Unlimited	2.5 hours
Protection needed	No	Yes

Why 20 dB is a bigger jump than it looks

A 20 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 70 dB to 90 dB therefore multiplies the acoustic energy by about 100× while your ear reports something closer to 4.0× as loud. Both statements are true — they simply measure different things.

Which one is safe?

70 dB is safe for unlimited exposure, but 90 dB is at or above the 85 dBA action level, where safe time is about 2.5 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 20 dB difference is to think in distance. Outdoors, every doubling of distance removes about 6 dB, so standing at 90 dB versus 70 dB is roughly like standing 10.0× closer to the same source. Conversely, moving about 10.0× further away would bring 90 dB down to 70 dB.

Adding the two levels together

Decibels do not add arithmetically. A 70 dB source running alongside a 90 dB source does not produce 160 dB — the correct total is 90.0 dB, calculated as 10 × log₁₀(10^(70/10) + 10^(90/10)). 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 90 dB much louder than 70 dB?

90 dB carries about 100 times the sound energy of 70 dB and is perceived as roughly 4.00 times as loud.

What is the difference between 70 dB and 90 dB?

The difference is 20 dB. 70 dB is comparable to a vacuum cleaner at 3 m, while 90 dB is comparable to a petrol lawn mower.

What do 70 dB and 90 dB add up to?

Combined, two sources at 70 dB and 90 dB produce about 90.0 dB — not 160 dB — because decibels add logarithmically.

Which is safe, 70 dB or 90 dB?

70 dB is below the 85 dBA action level and safe, while 90 dB is at or above it and needs an exposure limit.

See each level in detail

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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.