The Type 1390-B Random Noise Generator provides a high level of electrical noise at its output terminals. This type 'of signal is useful in-room acoustic measurements, loudspeaker and microphone tests, psychoacoustic tests, filter tests, crosstalk measurements for multichannel carrier systems, calibration checks on recording systems, modulation of signal generators and test oscillators, tests of RMS response of meters, observation of resonance in systems, electrical averaging of resonant responses, and comparisons of effective bandwidth.