https://www.patreon.com/AppliedScience ---- Donate here! I built a tiny radio into a ballpoint pen that allows the user to hear audio by casually biting the pen.
A horn-shaped speaker is louder than an equivalent speaker without the horn. This fact doesn't violate physics because the horn is acting as a matching device between the speaker and the air around it.
Photo Credit for phonograph: Norman Bruderhofer, Collection of John Lampert-Hopkins