White noise machine

White noise devices are available from numerous manufacturers in many forms, for a variety of different uses, including audio testing, sound masking, sleep-aid, and power-napping.

Sleep-aid and nap machine products may also produce other soothing sounds, such as music, rain, wind, highway traffic and ocean waves mixed with—or modulated by—white noise.

Republican Glen Casada had a white noise machine installed in his office to prevent against eavesdropping.

There is not a lot of research on the impact of loud sounds at inaudible frequencies (and their respective audible artifacts and harmonics).

Simple mechanical machines consist of a very basic setup, involving an enclosed fan and, optionally, a speed switch.