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

Sound intensity (loudness or volume using ELI5) is measured in decibels (dB), like a meter is measure of distance.

So let’s say a crowd of *one* person yelling is 60 dB. What happens if you bring in a second person yelling at 60dB?

Well, 60dB + 60dB does NOT equal 120dB. Because physics, 60dB + 60dB=63dB. When you double the intensity you gain 3dB,which isn’t very much.

So, using the doubling game, you’d need FOUR people to get to 66dB.

Honestly, I’m sitting on toilet right now, so I won’t continue to extrapolate from there. Let’s jump ahead.

Let’s say that you have a good sized crowd, 4000 people, and together they can make a pretty loud crowd roar, 85dB. If you had 8000 people, the noise would be 88dB. A 3dB step is barely noticeably loud. So it would take a lot more people to make a noise level of 100dB, which is pretty darn loud.

Of course this does not take into account the acoustics of the stadium, and not everyone make the same amount of noise, etc.

Hope this helps.