Evoked response audiometer for testing sleeping subjects

US5023783A · kind A · utility

Assignee

• The University of Melbourne · AU

Inventors

• Lawrence Thomas Cohen · Melbourne, AU
• Field W. Rickards · Melbourne, AU

Key dates

• Filing date: Jun 8, 1990
• Grant date: Jun 11, 1991
• Expiry date: Jun 8, 2010

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S128/92
• WIPO field: Medical technology
• WIPO sector: Instruments

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 amplitudes and phase angles of the signals, and for extracting from the means values of the phase angles the probabilities that the distributions of the phase angles could have occurred by change, whereby the existence of phase locking of the brain potential signals can be determined.