What happened, what changed, what did not.

The building was inspected before equipment was brought inside. Two loose windows, one active water line and a timed ventilation fan were identified. These were added to the environmental notes before any recording began.

At 21:17, a short impact was heard from the eastern stairwell. The same sound was reproduced by allowing the fire door to close from roughly ten centimetres.

Result

No unexplained activity was recorded during the baseline period. The stairwell sound should not be treated as evidence in later sessions unless its timing or character materially differs.

Three files contain a similar low-frequency pulse. The spacing is close, but not exact enough to describe as mechanically timed. Background hum was removed only from a working copy; the original recordings remain unchanged.

The strongest version begins beneath a spoken sentence, which makes accidental handling noise less likely but does not rule it out.

Access is limited to the ground floor and eastern stairwell. The upper floor remains structurally unverified and is outside the survey boundary. No participant should enter closed rooms or move existing objects.