Vocal

AllMusic groups this under the genre label "Vocal," which describes classic mainstream American pop performed by individual singers or vocal groups. Before rock and roll, pop vocalists did not write their own material. They interpreted songs written by professional songwriters like Irving Berlin, George Gershwin, and Cole Porter, usually backed by an orchestra or a big band (AllMusic, n.d.-r). Think of these singers less like songwriters and more like actors performing a script. The song already existed, and the singer's job was to bring their own interpretation to it.

During the 1930s and 1940s, vocalists became the true stars of the big band era. Singers like Bing Crosby and Frank Sinatra, along with vocal groups like the Andrews Sisters, became major names, and that generation shaped the vocal groups that followed in the 1940s and 1950s (AllMusic, n.d.-r). Wikipedia refers to this broader style as "traditional pop," a genre that generally predates rock and roll's rise in the mid-1950s and is also called "classic pop" or "pre-rock and roll pop" (Traditional pop, n.d.).

The songs at the heart of this genre are often called standards, or American standards, and the most celebrated ones make up what is known as the Great American Songbook (Traditional pop, n.d.). AllMusic credits songwriters like Jerome Kern, Irving Berlin, George Gershwin, and Cole Porter with supplying jazz and pop musicians an enormous well of material to draw from over and over (AllMusic, n.d.-s). A standard earns that name because it became a permanent part of the repertoire, unlike a song written for one record that gets forgotten (AllMusic, n.d.-s). Picture standards as sheet music every musician in the room already knows by heart. Anyone can pick it up and reinterpret it without starting from scratch.

Even after rock and roll took over the mainstream, some of the singers connected to this style kept their stardom, including Sinatra, Ella Fitzgerald, and Dean Martin (Traditional pop, n.d.). Many other vocalists moved into 1960s vocal jazz or a revived swing sound, sometimes labeled easy listening (Traditional pop, n.d.). This tradition has never fully disappeared either. It has been kept alive by contemporary jazz vocalists such as Tony Bennett, Diana Krall, and Norah Jones, as well as newer artists like Samara Joy, who continue interpreting these same standards for new listeners (AllMusic, n.d.-t).

Sources:

AllMusic. (n.d.-r). Vocal music genre overview. https://www.allmusic.com/genre/vocal-ma0000011877
AllMusic. (n.d.-s). Standards music genre overview. https://www.allmusic.com/genre/standards-ma0000011874
AllMusic. (n.d.-t). Contemporary jazz vocals music style overview. https://www.allmusic.com/style/contemporary-jazz-vocals-ma0000002966/artists
Traditional pop. (n.d.). In Wikipedia. https://en.wikipedia.org/wiki/Traditional_pop