Pretend ductwork

Around his plant-strewn work cubicle, low whirring air sounds emanated from speakers in the floor, meant to mimic the whoosh of conventional heating and air-conditioning systems, neither of which his 222,000-square-foot office building has, or needs, even here at 5,300 feet elevation. The generic white noise of pretend ductwork is purely for background and workplace psychology— managers found that workers needed something more than silence.
—"Soaking Up the Sun to Squeeze, NYT