Most folks rarely focus on music; it's background to other activities like talking, reading, working, exercising, and so forth. They don't really think about sound that much, as long as it's loud enough, or they can follow the dialogue, or there's enough bass, they're happy. Audiophiles are more likely to really listen, so we care about how our music or home theater sounds. The more you listen, the more you hear, and the opposite is also true.
I always liked music, but it was the sound of Jimi Hendrix's guitar feedback and distortion that sucked me in when I was 18. The rawness of the sound and the texture of it fascinated me. I started to notice how John Lennon double-tracked his vocals, he overdubbed a second vocal and sang along with himself on some Beatles tunes. The Beatles were always manipulating their vocals and changing the timbre, and I remember the first time I heard "Lady Madonna," I thought it was Ringo singing -- but it was Paul. His vocal sounded so different on that tune I didn't recognize him at first.
Home theater sound plays a supportive role to the image, but the best sound systems really do add a deeper dimension to the experience. Great mixes, like the one on "Avatar" put you inside the environment of the scenes. Director David Lynch ("Eraserhead,""Lost Highway," "Blue Velvet") told me years ago that he uses a lot of subliminal sounds in his mixes, sounds that are just barely audible, but sounds that create tension or cue the audience to react to onscreen action. That subtle stuff is lost over most systems and sound bars; you'll only hear those sounds from higher-end home systems or in the best movie theaters.
One of my audiophile buddies had his awakening at an early age, "When I was in fifth grade, my stepbrother took me to see Rush on their Power Windows tour. It blew my mind, and I made a promise to myself I'd be involved in music or sound, or both!!" Another one said he became aware when he started singing in the choir when he was seven.
At what age did you start thinking about sound? Share your experiences in the Comments section.