The Beatles and The Beach Boys

When I was listening to both Beach Boys Pet Sounds (1966) and The Beatles Revolver (1966), one thing that is apparent is that The Beatles is that the audio (the lyrics and instruments) has this distorted echo. In the song "I Want To Tell You" the instruments used, guitar, piano and drums sound dissonant/ out of sync with each other. It's as if the song was recorded, slowed down and then stretched out.  Now, I'm no musician. So a little research had to be done and it appears that they used a technique called automatic double tracking. This technique consisted of two tape recorders  linked together to create a double track. The tapes would be extended and voices would be dubbed over the recordings as well. The Beach Boys had a similar technique as well.

With the Beach Boys, the instruments are more harmonically in sync but also carries a reverb  amplifying the instruments and  voices. Making the performers like that they are performing on stage or in a large room.  The strategy they used to achieve this effect was to record each member's voice separately. Over 6- 8 tracks would be used, overdubbed and then mixed. The song "That's Not Me" and "Wouldn't It Be Nice" are prime examples of these mixes.