What is sound?
First there is silence in the room; then someone starts to play the violin. Does the violin make something called sound which travels across the room and arrives in me?
How could this be? The bow drawn across the violin string does not make anything that was not there before. The room is still and silent; the bow is drawn across the string. Nothing has been added that was not there in the silence a moment before. There is the same number of items in the room now as there was before.
But there is movement. The string is made to vibrate: it shakes rhythmically and makes the air adjacent to it shake too. And this vibration is passed on very quickly from the violin until it fills the room.
Air, invisible, shaking. But air shaking is not what we mean by sound.
The vibrations in the air reach my ear where their kinetic energy is transformed into chemical and electrical energy in the nerves connecting the ear to the brain.
But still there is nothing happening that could remotely be called sound. The brain receives this energy, processes it and is subtly altered by it. But a brain changed by energy is not sound.
This is a brief account of what is happening when we hear a sound. But it does not even begin to explain how it is we come to have the experience of hearing sound. Indeed, it seems to have nothing remotely in common with the sound. For what have a few million fidgeting neurons to do with a sound, a melody?
Now my description of the physics and biology of sound is not very technical. But if it were a thousand times more technical and detailed, would it come any nearer to explaining how the sequence of one physical event after another is related to the sound we hear?
Stretched horsehair, pushed, pulled
over taut wires pressed by fingers
fast as hummingbird wings
shakes air that tickles ears
that ruffles cells
that spark inside the brain
—ALL THIS IN SILENCE, IN UTTER SILENCE—
then, somehow, somewhere, the music plays.