why are crowds louder than small groups/individuals even if each person produces the same amount of noise? In other words why would a group of people, each generating noise at Xdb sound louder than an individual generating noise at Xdb? How does cumulative sound work?

Question

why are crowds louder than small groups/individuals even if each person produces the same amount of noise? In other words why would a group of people, each generating noise at Xdb sound louder than an individual generating noise at Xdb? How does cumulative sound work?

In: Physics

Answer 1

The rule of thumb is something like: it takes twice the power to result in a 3 decibel increase in volume. Basically, if a group of 10 people talk at 80dB, a group of 20 people will talk at 83dB.

Now 3dB doesn’t sound like much, but it’s a noticeable increase. Start stacking those up, and you’ll get a roaring crowd very quickly.

Of course, the reality is that people in progressively bigger groups will have to talk louder to be heard. So there’s natural escalation that happens as people fight the background noise.