In Over Her Head by Elsie Russell - Parnasse.com

one of those pins you could have heard drop, down below. Maybe she
was imagining things and they were just dust.
Then, a flash of white, and down below she saw in the
window's powdery glow a hunched green blob with wires trailing to a
silver square on the ledge. The battery must have run out, because the
only sounds were her breathing and the rain drumming away on the
stained glass outside. Eyes shut, she hovered, suspended inside the big
empty dome of her skull where black reality stretched out far beyond its
eggshell thin walls. She found her lungs and took a breath and instantly
was back in her seat under the window with the back of her tongue
tasting of ether and her entire body pulsing.
But now she knew something she had not known before. There
had to be a modulator to her alpha waves. Something was modifying
the amplitude, and more bizarre, the pitches of her composition. A
complete Fourier analysis would shed a ray or two of light on the
problem.
156