Eli5: Why does same sound source get louder if multiplied?

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When I start my boy’s plastic train on a plastic track it has a certain decibel. But when I add many of the same type of train (with same decibel?) on the same track system, I percive the volume to increase, why is that?
I’m not sure it’s the same in a crowd since people tend to raise their voice to be heard when many others are speaking at the same time

In: Physics

2 Answers

Anonymous 0 Comments

For the same reason when you drop two rocks in a lake and the crests of those waves meet each other, the resulting wave will be larger. That’s constructive interference. Constructive interference.

When the crest of the wave meets a trough of the other wave, they will cancel each other out. But your ear ignores the absence of sound. Destructive interference.

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