`If the main frequency were a C on a piano, the overtone would be the next higher G—a perfect fifth, and the interval of the first two notes in the melody of El

`If the main frequency were a C on a piano, the overtone would be the next higher G—a perfect fifth, and the interval of the first two notes in the melody of Elvis Presley’s hit “I Can’t Help Falling in Love with You.”` My read is that it's just saying that the first smaller frequency was the same ratio from the primary as G to C are in sound frequencies, so they're describing it as a similar interval as the first two notes, not as being literally the same tune.