I don't know what she's listening to, coming down the street, head bobbing almost imperceptibly to the beat in her ears.
Whatever it is, it makes her smile at strangers.
A smile too is a kind of music.
Yours, for instance, could fill a stadium.
The traffic, the security, the restless crowd. The sudden hush as you walk out on stage. The faces flickering to life one by one, as the audience starts to smile along.