Trained singers shape their mouths to act like speakers
While a human voice naturally dissipates most of its energy as heat, elite vocalists use internal geometry to amplify their sound ten times over without any extra effort.
A singer hitting a high note on a stage like American Idol is doing more than just vibrating their vocal cords. While the larynx produces the initial sound, most of that energy is lost as heat unless the performer reshapes their throat into a Helmholtz resonator—the same physics that makes a glass bottle hum when you blow across the top. By adjusting the volume of their mouth and the length of their neck, singers create vocal formants, which are specific frequency peaks that act like a natural megaphone. This technique allows a performer to project over a loud orchestra or a screaming crowd while using only a fraction of the physical strain an untrained person would endure.