Using a sound level meter to measure various sounds for comparison, The Backyard Scientist found that one megaphone is 79.7 decibels while using 10 only rose to 81 decibels.
When lined up in a circle, the megaphones created a literal feedback loop that rose off the charts, reaching nearly 120 decibels — the highest the sound level meter can go.
The video explains it a lot better with big important science words as to why that is.
So, when it comes to talking with megaphones, it’s better to just stick to one.