Abstract: The purpose of this study is to characterize auditory filters at low frequencies, defined as below about 100 Hz. Three experiments were designed and executed. They were conducted in the Exterior Effects Room at the NASA Langley Research Center, a psychoacoustic facility designed for presentation of aircraft flyover sounds to groups of test subjects. The first experiment measured 36 subjects’ hearing threshold for pure tones (at 25, 31.5, 40, 50, 63 and 80 Hz) in “quiet” conditions. The subjec…