Listen to some popular music of the late 1950s and early 1960s. You can get a sense of the landscape from Tom Breihan’s wonderful column The Number Ones, which reviews every number one hit on the Billboard Hot 100 from 1958 to the present:
Pop music before the Beatles sounds very old-fashioned, tame, and well-behaved. Listen to Cliff Richard, one of their early competitors, and you’ll see what I’m talking about. He sings well, the song is perfectly fine, it just doesn’t have much of an edge to it.
Now listen to an early Beatles song. Hear how much younger and fresher they sound, how unpolished and even rough they are. It was unusual for singers to have regional working-class accents, usually they worked hard to suppress them. Also, the Beatles’ hair was very long for the time, and that made them threateningly gender-fluid. Their singing style is informed by the Isley Brothers or Little Richard, and few white people were listening Black music back then.
As you go through the Beatles albums in chronological order, you will start hearing strange things: backwards guitar solos, slowed-down and sped-up voices and instruments, overdubbed soundscapes, timbres that are hard to identify. A song like “Tomorrow Never Knows” isn’t as shocking now as it was when it was released, because we are used to pop songs being psychedelic dreamscapes. But back in 1965, you expected rock to sound like people playing instruments in a room, and this would have sounded like nothing you had ever heard before.
It’s also interesting to listen to the Rolling Stones around this time, to see how closely they were trying to imitate the Beatles’ studio innovations. And it’s interesting to listen to the Beach Boys, who had a friendly rivalry with the Beatles and who were similarly ambitious in their work in the recording studio.
I like the Stones and the Beach Boys fine, but for me, nothing compares to the Beatles’ songwriting or production.
The Beatles didn’t single-handedly break any musical or technical ground. But they drew on a much wider palette of influences than rock or pop bands had before, and they brought a lot of ideas from the avant-garde into the pop mainstream. Karlheinz Stockhausen was cutting up tape into loops long before the Beatles did it, but few people ever heard his music. The Beatles were so huge that any strange new thing they tried in the studio would be eagerly studied (and copied) by uncountably many other musicians.