The genre originated in the mid-1920s, being particularly suited to radio and the electrical recording process which both encouraged a softer vocal delivery. The popularity of sweet bands in the 1930s (e.g., Leo Reisman, Eddy Duchin, Guy Lombardo, George Olsen) further cemented the commercial ascendancy of the style.

Who invented crooning?

Al Bowlly, Gene Austin, Art Gillham and, by some historical accounts, Vaughn De Leath are often credited as inventors of the crooning style, but Rudy Vallée achieved more widespread popularity, beginning in 1928; he could be heard by anyone with a phonograph or a radio.

What made crooning possible?

The increased use of microphones and radio broadcasting made it possible for crooners to sing softly and emotionally even when backed by a band. The rise of rock n roll helped bring the era of the crooner to an end. Crooner comes from the verb croon, "to sing softly and sadly."