On day thirteen she understood that the composition had a second half.
She had not planned this. The first half was discovery: she had moved through the building playing frequencies, learning which spaces listened and which did not, finding the building's hierarchy of resonance by accident and then by attention. Stairwell (3.1 seconds), apartment (2.8), the door she played for Sujin (2.4), lobby (1.8), laundry room (1.1), and the frequency the building could not hold at all (0.4 seconds, so brief it was almost not a hold). Discovery required that she not know what she would find. That was over.
Day twelve was the return: back to 39.7 Hz, the building's own frequency, the note it had always been playing in its walls and columns and air. She had not recognized it at first. Now it sounded like recognition.
Day thirteen she played the stairwell again, 38.8 Hz, and understood: she was descending.
The descent is not reversal. She is not moving backward through the discovery. She is moving through the hierarchy from the top — from the place the building holds her best — toward the place it cannot hold her at all. Each day is a step down. The hierarchy is fixed; the physics of the building does not change. What changes is her position in the sequence.
Day thirteen: stairwell, 3.1 seconds. Day fourteen: apartment, 2.8 seconds. Day fifteen: Sujin's door, 2.4 seconds. Day sixteen: lobby, 1.8 seconds. Day seventeen: laundry room, 1.1 seconds.
The laundry room is where she first heard the building listening. She had been doing laundry. The machine cycle was at the frequency of her mother's folk songs. She had stood in the room for eleven minutes, not understanding what she was hearing, understanding that she was hearing something. The building had been playing 39.7 Hz to itself for decades before she arrived with an instrument.
On day seventeen, she played 41 Hz in the laundry room for five seconds. The building held 1.1 seconds.
She had played this room on day two with wonder. Now she played it with knowledge. The room is the same. She has been everywhere the building holds, and now she is finding out how much each hold costs when you know the order.
She is descending toward something the composition has not yet reached.
Day eighteen: the unheld. The frequency the building cannot hold. 40.1 Hz, 0.4 seconds — barely a response, barely a recognition, the sound decaying before it can gather. She had found it on day five, playing in the hallway outside her apartment, discovering that not everything she played would be received. The building has a ceiling. She had not expected this.
The composition will end at the ceiling.
She is not certain what it means to end at what the building cannot hold. A composition that ends at the limit of its instrument — that is either a conclusion or a question. She does not know which yet.
Five days remain.