The Vocoder (1940)
Before Auto-Tune, the Vocoder reigned as our primary tool for manipulating and messing with a singer's pitch (i.e. a vocal synthesizer). Created by a Bell Labs physicist to secure compressed voice transmissions over phone lines, it became essential during WWII in obscuring trans-Atlantic conversations between President Roosevelt and Winston Churchill. Three-plus decades later, groundbreaking German electronic band Kraftwerk made it commonplace in popular music, where it would later be notably adopted by the unlikely one-two punch of Cher and Daft Punk.