I have never really fully understood how a speaker vibrating air molecules which then in turn vibrate the membrane in your ear works. How can a speaker make multiple sounds at the exact same time if its based on movement of a physical object?
In: Physics
Sounds are waves. “Pure sounds” are perfectly shaped sine waves, but composite sounds happen because of a property of waves that [they can add up](https://www.mq.edu.au/__data/assets/image/0003/911307/waveadd01.gif), basically the effect of simple sine waves all compounded onto a single “complex” wave.
If you want to visualize it, the [surface of the ocean](https://www.miros-group.com/wp-content/uploads/2019/02/Dry-IoT-wave-radar-1200×800.jpg) has bass (the big swells), and also high pitched “sounds” in the little waves created by the wind. A fishing floater on that surface would “feel” both the bass (big waves) and the high pitched sounds (small waves) at the same time.
So you recognize drums vs. violins vs. trumpets vs. the voice of the opera singer because your brain is very good at decomposing the “complex” wave it hears, to the individual waves. Part of the process of “decomposition by frequency” is your [inner ear](https://i.pinimg.com/originals/40/71/85/4071852705126baeb83cef993aaf8aca.jpg), where the sound waves from outside go around this spiral of hairs and sensors, and the sound frequencies are “separated” by the hairs at one end vibrating with only the deep sounds, whereas the much more fine hairs at the other end vibrate only with the high pitched sounds. So your inner ear splits the sound into multiple frequencies.
And then the brain takes it from there and recognizes not just frequencies, but also that they belong to certain instruments, or voices belong to certain people, and not only that, but your brain figures out the *meaning* behind words. Brain does the same with light, by the way: light frequences are color, you see color, but you don’t just see splotches of color, you recognize objects, faces, *emotions on faces*.
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