Question 1

Why do we use decibels instead of regular units?

Accepted Answer

The range of sound intensities humans can hear spans about 12 orders of magnitude (from 10⁻¹² to 1 W/m²). A logarithmic scale compresses this enormous range into a manageable 0–120 dB scale. It also better matches how our ears perceive sound, since perceived loudness increases roughly logarithmically with intensity.

Question 2

How much louder is a 10 dB increase?

Accepted Answer

A 10 dB increase represents a tenfold increase in sound intensity. However, humans perceive a 10 dB increase as roughly twice as loud. A 3 dB increase doubles the intensity, a 20 dB increase means 100 times the intensity, and a 30 dB increase means 1,000 times the intensity.

Question 3

Can you just add decibel levels together?

Accepted Answer

No. Because decibels are logarithmic, you cannot simply add them. Two 60 dB sources produce about 63 dB, not 120 dB. To combine dB levels, you must convert each to linear intensity, add the intensities, then convert back to dB. This calculator handles that conversion for you.

Question 4

What are typical dB levels?

Accepted Answer

Common reference points: whisper ≈ 30 dB, normal conversation ≈ 60 dB, vacuum cleaner ≈ 70 dB, city traffic ≈ 85 dB, rock concert ≈ 110 dB, jet engine at 30 m ≈ 140 dB. Prolonged exposure above 85 dB can cause hearing damage.

Decibel (dB) Calculator

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