eli5: How a simple cone can amplify the sound?

Question

That wouldn’t require some way to add energy to the sound?

In: 10

Answer 1

It doesn’t amplify sound, it reduces losses. Sound can travel in all directions from its source. Most directions are not towards the intended audience, and so the energy propagating in those directions is wasted. A cone allows the vast majority of the sound to travel only in one direction so nearly all of the energy from the sound’s source goes towards the intended audience.

The intended audience *does* receive more energy, but the source does not use/produce more energy. The energy is focused mostly in one direction.