[jddj]

An older guy from the rave scene once taught me this without explaining the process at all.

When we'd be out and loud music was playing and somebody couldn't hear what he was saying to them, he'd lean in, speak more softly and place a finger lightly on the front part of their ear (so as to not put his finger in their ear).

He was always much easier to understand one he had done that, and we all picked up the habit. We weren't sure if the finger acted as a conductor, or what the explanation was, but reducing the dynamic range seems like a really good explanation.