I was so attuned to the sounds of our 15 that there were rock songs on the radio that I discovered had some similar rhythms, like the surging as the machine filled and the pump was gulping water and air, making those little pulsating fountains above the jets in the 4 way HydroSweep, if you held the door safety switch and watched the start of the fill. Woe to anyone who released the switch and then pushed it in again when the pump had all water and not air and water over the intake! You got a power facial, and shampoo along with a partial ceiling and floor washing. One place I could hear it was in the Doors Light My Fire as the music builds in the lead up to the opening vocal passage. The smooth steady sound of the circulation could be heard in Scott McKenzie's If You're Going to San Francisco and near the end of the song, there is a passage where he sings, "If You're going to San Francisco" without all of the instruments behind him that sounds like after the drain valve opened when the sump is empty and it's just the hum of the motor.
The 15, installed in 1966, was still in the house and still working when we sold it around 2004 or so.