Patent No. 5023783 Evoked response audiometer for testing sleeping subjects
Patent No. 5023783 Evoked response audiometer for testing sleeping subjects (Cohen, et al., Jun 11, 1991) Abstract An evoked response audiometer for sleeping subjects comprising a function generator for supplying to a sleeping patient an auditory signal consisting of a carrier frequency which is periodically modulated at frequencies in excess of 60 Hz, the frequency of modulation being varied in a generally increasing manner for auditory signals of higher frequencies such that the stimulus is frequency specific, a detector for sampling and analyzing brain potentials evoked by said signal, a low-pass filter providing a time window which samples the brain potentials for a predetermined interval to provide sets of fourier analysis samples containing amplitude and phase data in narrow bands centered on the modulation frequency and its second harmonic, a computer for analyzing the Fourier analysis samples to extract means values of the a