Underground HVAC Drone All Night
10 Hours of Subterranean Mechanical Hum for Deep Sleep

A dense, tunnel-dwelling HVAC drone captured as if you were sitting in a basement mechanical corridor at three in the morning. The core tone is low and enveloping with a thin layer of airflow whisper sitting just above it, never drifting, never sharpening.
Engineered with zero modulation across the full ten hours, so the soundbed stays identical from minute one to minute six hundred. Loop points are inaudible.
The texture is thicker than standard white noise and warmer than typical brown noise, splitting the difference for listeners who find pure brown too muffled and pure white too hissy. Perfect for basement apartments, mid-rise units near elevator shafts, remote workers sharing walls with noisy neighbors, and anyone who sleeps best to the subterranean hum of a large building breathing around them.
Faint mechanical resonance shifts in the lowest registers without ever pulling attention upward, and the air feels still and pressure-equalised — like resting deep inside a quiet building. Perfect also for shift workers and city dwellers who need a reliable sound shield against unpredictable urban noise. Put it on, dim the lights, and let the underground drone hold the night together.