Hearing evaluation device with noise detection and evaluation capability

• US 7,133,715 B1
• Filed: 01/07/2000
• Issued: 11/07/2006
• Est. Priority Date: 01/07/2000
• Status: Expired due to Fees

• Current Assignee: Natus Medical Incorporated
• Original Assignee: Natus Medical Incorporated
• Inventors: Smits, Matthijs P., Flaherty, Bryan P.
• Primary Examiner(s): Chin, Vivian
• Assistant Examiner(s): Faulk, Devona E.
• Application Number:
  US09/479,548
• Time in Patent Office: 2,496 Days
• Field of Search: 381/60, 600/559, 600/300, 600/544
• US Class Current: 600/544
• CPC Class Codes: A61B 5/121 evaluating hearing capacity
• CPC Class Codes: A61B 5/38 Acoustic or auditory stimuli
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal

Abstract

An apparatus and method for evaluation of hearing loss is disclosed. The apparatus and method use evoked Auditory Brainstem Responses (ABR) to determine if the subject is able to hear click stimuli that are repeatedly administered. In order to facilitate efficient differentiation of the ABR from the accompanying noise, normative data is used to detect test conditions where physiological, non-physiological, and ambient acoustic noise would interfere with the progression of test.

Claims

1. A device for hearing evaluation of a subject comprising:

means for repeatedly delivering an auditory stimulus;

means for sampling an EEG response to said stimulus;

means for detecting when non-physiological noise is associated with said EEG response, for automatically determining the amount of said non-physiological noise, and for automatically determining when said amount is excessive relative to a threshold, wherein said threshold is derived from normative data; and

pausing means for pausing the evaluation when said amount is excessive relative to said threshold.

2. A method for hearing evaluation of a subject, comprising the steps of:

repeatedly delivering an auditory stimulus;

measuring the EEG response to said stimulus;

detecting the noise associated with said EEG response;

automatically detecting the amount of said noise;

automatically determining that said amount is excessive relative to a threshold, wherein automatically determining that said noise amount is excessive relative to a threshold comprises computing a composite signal noise variance;

comparing said composite signal noise variance to a predetermined threshold; and

determining that the composite signal noise variance is greater than said threshold.

3. The method according to claim 2, further comprising the step of pausing the testing in response to determining that said noise amount is excessive relative to a threshold.

4. The method according to claim 3, further comprising the step of determining if said EEG response contains an ABR waveform.

5. A method for hearing evaluation of a subject, comprising the steps of:

repeatedly delivering an auditory stimulus;

measuring EEG responses to said stimulus, said EEG responses having amplitudes;

detecting noise associated with said EEG responses;

determining a degree of polarity bias in said EEG responses;

determining when said bias is excessive relative to a threshold;

whereby determining when said polarity bias is excessive relative to a threshold comprises

digitizing said EEG response;

transforming said digitized EEG response into a series of binary numbers corresponding to the polarity of the amplitude of said EEG response;

transforming said binary numbers into an array of polarity sums;

determining the bias in said array of polarity sums; and

comparing said bias to a predetermined threshold.

6. The method according to claim 5, whereby determining when said polarity bias is excessive relative to a threshold comprises:

determining the difference between the mean and the median amplitude in said EEG responses; and

comparing said difference to a predetermined threshold.

7. The method according to claim 5, further comprising the step of pausing the testing in response to detecting excessive levels of polarity bias in said noise.

8. The method according to claim 5, further comprising the step of determining if said EEG response contains an ABR waveform.

15. The method according to claim 5 wherein said noise comprises non-physiologic (asymmetric) noise and symmetric noise further comprising the step of detecting said non-physiologic (asymmetric) noise separate from said symmetric noise.

9. A method for hearing evaluation of a subject, comprising the steps of:

repeatedly delivering an auditory stimulus;

measuring EEG response to said stimulus;

detecting the noise associated with said EEG response;

determining the amount of said noise;

determining the degree of polarity bias in said EEG response;

determining when adverse evaluation conditions are present, based upon both said noise amount and said noise polarity bias;

pausing the step of determining the degree of polarity bias in said EEG response.

16. The method according to claim 9 wherein said noise comprises non-physiologic (asymmetric) noise and symmetric noise further comprising the step of detecting said non-physiologic (asymmetric) noise separate from said symmetric noise.

10. A method for hearing evaluation of a subject which comprises the steps of:

repeatedly delivering an auditory stimulus to a subject;

measuring an EEG response to the stimulus said response having a amplitude polarity at each point in time;

digitizing said EEG response;

transforming said digitized EEG response into a series of binary numbers corresponding to the polarity of the amplitude of said EEG response;

transforming said binary numbers into an array of polarity sums;

detecting the noise associated with said EEG response;

determining the amount of said noise;

automatically detecting when said amount is excessive relative to a threshold;

accounting for any excessive amounts of said noise; and

determining if an EEG response contains an ABR waveform by comparing the array of polarity sums against normative data;

wherein the step of accounting for excessive amounts of said noise comprises pausing the evaluation.

11. A method for hearing evaluation of a subject which comprises the steps of:

repeatedly delivering an auditory stimulus to a subject;

measuring an EEG response to the stimulus said response having a amplitude polarity at each point in time;

digitizing said EEG response;

transforming said digitized EEG response into a series of binary numbers corresponding to the polarity of the amplitude of said EEG response;

detecting the noise associated with said EEG response;

determining the amount of said noise;

automatically detecting when said amount is excessive relative to a threshold;

accounting for any excessive amounts of said noise; and

determining if an EEG response contains an ABR waveform by comparing the array of polarity sums against normative data,

wherein the step of accounting for excessive amounts of said noise comprises rejecting a portion of said array of polarity sums.

12. A method of evaluation for hearing loss which comprises the steps of:

repeatedly delivering an auditory stimulus to a subject;

measuring an EEG response to the stimulus said response having an amplitude polarity at each point in time;

digitizing said EEG response;

transforming said digitized EEG response into a series of binary numbers corresponding to the polarity of the amplitude of said EEG response;

transforming said binary numbers into an array of polarity sums;

detecting the noise associated with said EEG response;

detecting the degree of polarity bias in said EEG response;

determining when said bias is excessive relative to a threshold;

accounting for any excessive bias; and

determining if an EEG response contains an ABR waveform by comparing the array of polarity sums against normative data.

13. The method according to claim 12, wherein the step of accounting for any excessive polarity bias comprises pausing the evaluation.

14. The method according to claim 12, wherein the step of accounting for any excessive polarity bias comprises rejecting a portion of said array of polarity sums.

17. The method according to claim 12 wherein said noise comprises non-physiologic (asymmetric) noise and symmetric noise further comprising the step of detecting said non-physiologic (asymmetric) noise separate from said symmetric noise.