Monosensory Surgery

The singer goes downstairs,
Voice floating up the well,
A winding melody,

Not a popular tune,
Something too old to tell.
This indicates you must

Be on the upper floor
Listening to that voice
Coming from the forest

Of the lower darkness.
You must be trapped above.
You are reasoning hard,

Struggling to find your way
To a world where you know
Where you are, like Laura

Bridgman in the marble
Cell, reaching out by touch,
But for you, down to sound

Not touch, no touch, just song
Floating up from below.
Below? How can you tell?