Evoked response audiometer
First Claim
1. An evoked response audiometer comprising means for supplying to the patient under investigation an auditory signal modulated by a continuous frequency waveform over a plurality of cycles of said waveform, to thereby evoke phase-locked steady state potentials in the brain of the patient, and means for recording evoked brain potentials evoked by said signal, whereby phase-locking of said steady state recorded potentials to the modulated auditory signal may be determined characterized in that said auditory signal is presented in a frequency specific continuous modulated form for an extended period of time to evoke phase-locked steady state potentials in the brain.
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Abstract
An evoked response audiometer is disclosed in which the patient is presented with a continuous auditory signal which is amplitude modulated and the evoked brain potentials of the patient (EEG) are recorded. The potentials are amplified and filtered and are averaged over a number of sampling periods to improve the signal to the noise ratio. The averaged signals are then analyzed to determine the amplitude and phase of the main components of the response to determine whether phase locking has occurred. The phase of the main components is then plotted against variation of the modulating frequency and the gradient of the plot provides the latency of the response from which neurological and other factors of significance to the hearing of the patient may be determined. The sound pressure level of the auditory signal is also varied and the amplitude and phase of the response plotted against these changes to provide an indication of the sensitivity of the hearing of the patient.
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10 Claims
- 1. An evoked response audiometer comprising means for supplying to the patient under investigation an auditory signal modulated by a continuous frequency waveform over a plurality of cycles of said waveform, to thereby evoke phase-locked steady state potentials in the brain of the patient, and means for recording evoked brain potentials evoked by said signal, whereby phase-locking of said steady state recorded potentials to the modulated auditory signal may be determined characterized in that said auditory signal is presented in a frequency specific continuous modulated form for an extended period of time to evoke phase-locked steady state potentials in the brain.
- 7. A method of objectively testing the hearing of a patient, comprising the steps of presenting to the patient for an extended period of time an auditory signal modulated by a continuous frequency waveform over a plurality of cycles of said waveform to thereby evoke phase-locked steady state potentials in the brain of the patient, recording the brain potentials evoked by said signals, and analyzing said recorded potentials to determine whether they are phase-locked steady state potentials.
Specification