There was a hum in the air, a fast-cycling white noise that filled the room. The room’s one door was closed, and its windows, in order for the machine making the noise to have its full effect. The machine was a powerful air purifier, an allergy-related device designed to pull dust from the room and adhere it to an easily removable filter, a robust one that could last months before disposal. The hum wasn’t merely a presence in the room. When turned on, the device’s fuzzy droning consumed the room. Like a quiet talker who draws in listeners, the machine seemed to pull the walls closer, an impression furthered by the closed door and windows. The outside world lost any presence. Not a siren or a bird or a passing bus was heard for the duration. The use of the machine was never a claustrophobic experience —Â never a claustrophonic experience. There was an intimacy to it, womb-like, comforting. The therapeutic purpose of the machine provided a positive association with the hum. I wondered if the company that manufactured the machine had worked to tune it, to give it a hum that was pleasant despite being so present, one that felt ameliorative rather than threatening. I wondered if, over time, the hum might alter — erode, degrade — and someone, the equivalent of a piano tuner, would have to come to my home and adjust it.