This picture shows the Random Noise Generator Type 1390-B produced by the General Radio Company in West Concord, MA. A random noise generator is a device for creating standardized levels of noise for the purposes of measurement and experimentation. The device’s Operating Instructions list “room acoustic measurements, loudspeaker and microphone tests, psychoacoustic tests,” and many other domains as possible areas of use. Although, historically, sound-reproducing devices were plagued by many kinds of sound distortion and unwanted background noise, a clearly defined noise signal can only be obtained using a special apparatus such as this one. Noise-generating circuits were commonly used in analog synthesizers to create percussive and special-effect sounds, and the creation of an unpredictable signal with a high level of randomness has also been important for applications related to encryption and the simulation of physical processes. The model pictured here can create different configurations of noise, including signals that transcend the human hearing range by many orders of magnitude. Its operation is demonstrated in the accompanying video.