The Decibel Scale: Why It Is Logarithmic
Decibels do not add up the way ordinary numbers do. The scale is logarithmic, so every 10 dB increase means the sound is about 10 times more intense — and roughly twice as loud to your ears.
Key points
- Every +10 dB = 10× the sound intensity (energy).
- Every +10 dB sounds about twice as loud to human ears.
- So 90 dB is 10× the intensity of 80 dB, and 100 dB is 100× the intensity of 80 dB.
- This is why small-looking dB differences matter so much for safety.
- A jump from 100 to 110 dB is a huge increase in energy hitting your ear, not a 10% one.
FAQ
Is 70 dB twice as loud as 35 dB?
Not exactly — loudness roughly doubles every 10 dB, so 70 dB is perceived as far more than twice 35 dB. The scale is logarithmic, not linear.
Why can’t I just add decibels?
Because they are logarithmic. Two 80 dB sources combine to about 83 dB, not 160 dB. See our guide on adding decibels.
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