What realization regarding vocal projection drove the eventual invention of true acoustic horns?

The need to *amplify* or *focus* sound rather than just raising its origin point.

The consistent failure of older methods, particularly elevation, to overcome the challenge of high ambient noise levels in large settings—like construction sites or bustling public squares—led to a critical understanding of acoustic needs. Speakers realized that simply placing the voice source higher (elevation) did not solve the problem of the sound being drowned out by engines, commerce, or excited crowds. This drove the necessity for a device capable of *amplifying* or actively *focusing* the sound energy itself, rather than merely changing where the sound originated. This physical collection and focusing of energy is the principle that early acoustic cones, the precursors to modern megaphones, were eventually developed to satisfy.