The musical track that runs in my head is not always present, but it is present far more than I wish it to be. There's always some song bouncing around in there - for hours, days or even weeks. It's not even limited to songs I like. Many times it is like a loop which runs over and over. "And we began to ro-ock - steady - steady rockin' all night long (all night lo-ong!)." Like that. It's been in there for three or four days. I picked it up like some virus while driving to Austin and listening to 1970s music. Sure, I like the song, but hadn't thought of it in years. Now, it's there every time the room grows quiet.
Christmas songs. Church songs. Sports songs. Popular songs. They all live in my head, and my musical brain never shuts up singing them to me. Honestly, it gets old, but it's entertaining as well.
If only people knew how often in conversation they say something which contains a phrase from some song, and my musical brain is off searching for that song, and when the lyric is found, starts singing it to me. Just say "don't stop believing," and see how fast Journey circa 1981 starts playing in my head.
My calculator brain would probably alarm some people. When I'm walking, often I'm counting steps. Not every step. Every other step. One count per two steps. That's a second of walking. That's five feet of distance. Take one hundred steps, that's one hundred seconds, which is one minute and forty seconds. It's one hundred steps times five feet, which is five hundred feet, which is almost one tenth of a mile.
Sometimes I combine the stepping thing with some other calculation. How many feet wide is this property? How many feet deep is it? Once I figure it is two hundred feet by two hundred fifty feet, I know it is 50,000 square feet, which divided by 43,560 (the number of square feet in an acre) is roughly 1.15 acres. I make these kind of calculations in my head constantly, every day, even when walking from a parking lot to a store.
Miles per gallon of gasoline? I track it in my head. How many miles have I driven? How many gallons have I used? How many miles per gallon am I getting? I know the computer in the car keeps track of this stuff, but I find its numbers less than precise.
You don't even want to know about my system for analyzing sports numbers. I break down things into thousands of a second for players, so I can compare their production in various categories on a per minute played basis. I do this so I can compare "apples to apples" among players.
Meanwhile, my third brain, the one I'm using now, is running all other systems. It may be writing, typing, or both. It may be watching television and reading at the same time. If I'm awake, it is cranking out something. But the music is a constant, and the calculations never end. It's been this way for decades, so I should probably get used to it.