Decibels

Why loudness is logarithmic

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Intensity falls as $1/d^2$: double the distance and the level drops by about 6 dB.
• $L = 10\log_{10}(I/I_0)$. Every +10 dB is 10× the intensity, and +3 dB is double.
• Above about 85 dB, long exposure can damage hearing.

Steps

1. Intensity
2. An enormous range
3. Compare two sounds
4. Walking away
5. Add a second speaker
6. From the formula