Abstract: In accordance with the Hall effect, a magnetic field applied perpendicular to the direction of current flow through a conductor causes an electric field perpendicular to both the direction of the current flow and the direction of the magnetic field established in the conductor. This effect has been used to produce magnetic field and current detectors, modulators and frequency doublers. In accordance with the present disclosure a portion of the magnetic field is reversed to produce squaring of or obtaining the square root of the amplitude of the voltage used to produce the conductor current.

Abstract: A binaural sound recording and reproduction system which utilizes a recording mannequin equipped with an electroacoustic model of the human auditory tract to thereby record the sound pressure which would be incident on a listener's eardrum and also utilizes a headset with in-ear transducers or receivers which exhibit a flat frequency response as measured at the listener's eardrums is described. The receiver units utilize acoustic impedance matching to the listener's ear canal to effect the flat frequency response characteristic. An electrical equalizer circuit to facilitate the use of the subject in-ear receivers with conventionally recorded sound is also disclosed.