Tinnitus Testing Device and Method

Abstract

Objectively identifying an acoustic characteristic of tinnitus of a subject. The subject is exposed to a sound pattern having a background acoustic signal preceding an audible silence. The background acoustic signal has a selected acoustic characteristic. An electrical response of the subject's central nervous system to the exposure to the sound pattern is measured. The measured electrical response has a first portion representing the electrical response of the subject's central nervous system to the background acoustic signal, and a second portion representing the electrical response of the subject's central nervous system to the audible silence in the sound pattern. The first portion of the measured electrical response is compared to the second portion of the measured electrical response and a determination is made as to whether the subject has tinnitus with an acoustic characteristic similar to the selected acoustic characteristic based on the comparison.

1 . A method for objectively identifying an acoustic characteristic of tinnitus of a human or animal subject comprising:
 selecting an acoustic characteristic of a background acoustic signal;   exposing the subject to a sound pattern, said sound pattern including a background acoustic signal having the selected acoustic characteristic and an audible silence, the background acoustic signal preceding the audible silence;   measuring an electrical response of the subject's central nervous system to the exposure to the sound pattern, said measured electrical response having a first portion representing the electrical response of the subject's central nervous system to the exposure to the background acoustic signal, and said measured electrical response having a second portion representing the electrical response of the subject's central nervous system to the exposure to the audible silence in the sound pattern;   comparing the first portion of the measured electrical response to the second portion of the measured electrical response; and   determining whether the subject has tinnitus with an acoustic characteristic similar to the selected acoustic characteristic based on said comparison.   
   
   
       2 . The method of  claim 1  wherein selecting the acoustic characteristic of the background acoustic signal includes selecting a value for one or more of the following parameters of the background acoustic signal: frequency, amplitude, and waveform. 
   
   
       3 . The method of  claim 1  wherein said comparing includes a first comparison and a second comparison, said first comparison comparing the first portion of the measured electrical response to the second portion of the measured response, said second comparison comparing the measured electrical response to a control electrical response, said control electrical response being a measured electrical response of the subject's central nervous system to a sound pattern having a background acoustic signal that is acoustically different from the subject's tinnitus, and wherein said determining includes determining whether the subject has tinnitus with an acoustic characteristic similar to the selected acoustic characteristic based on the first comparison and the second comparison. 
   
   
       4 . The method of  claim 1  further comprising:
 adjusting the selected acoustic characteristic based on said comparison of the first and second portions of the measured electrical response;   exposing the subject to a subsequent sound pattern, said subsequent sound pattern including an adjusted background acoustic signal having the adjusted acoustic characteristic and an audible silence, the adjusted background acoustic signal preceding the audible silence;   measuring the electrical response of the subject's central nervous system to the exposure to the subsequent sound pattern; and   determining whether the background acoustic signal having the selected acoustic characteristic more closely approximates the subject's tinnitus than the adjusted background acoustic signal having the adjusted acoustic characteristic as a function of the measured electrical response of the subject's central nervous system to the sound pattern compared with the measured electrical response to the subject's central nervous system to the subsequent sound pattern.   
   
   
       5 . The method of  claim 1  wherein the background acoustic signal preceding the audible silence in the sound pattern has a first duration and the audible silence in the sound pattern has a second duration shorter than said first duration. 
   
   
       6 . The method of  claim 5  wherein the second duration is between about 50 and 200 milliseconds. 
   
   
       7 . The method of  claim 1  wherein comparing the first portion of the measured electrical response to the second portion of the measured electrical response includes comparing the magnitude of the electrical response measured while the subject was exposed to the background acoustic signal to the magnitude of the electrical response measured after a pre-defined period following the subject's initial exposure to the audible silence in the sound pattern. 
   
   
       8 . The method of  claim 7  wherein the pre-defined time period is between about 20 and 300 milliseconds. 
   
   
       9 . The method of  claim 1  wherein comparing the first measured electrical response to the second measured electrical response includes computing a gain between the first measured electrical response and the second measured electrical response, and wherein said determining includes determining the subject does not have tinnitus with an acoustic characteristic similar to the selected acoustic characteristic when the computed gain is greater than or equal to a pre-defined threshold value and determining the subject does have tinnitus with the acoustic characteristic similar to the selected acoustic characteristic when the computed gain is less than the pre-defined threshold value. 
   
   
       10 . A method for objectively measuring tinnitus of a human or animal subject comprising:
 receiving an input signal representing an electrical response of the subject's central nervous system to a sound pattern, said sound pattern including a background acoustic signal qualitatively similar to the subject's tinnitus and an audible silence;   storing the received input signal;   identifying a first portion of the stored signal representing the electrical response of the subject's central nervous system to the background acoustic signal;   identifying a second portion of the stored signal representing the electrical response of the subject's central nervous system to the audible silence; and   comparing the identified first portion of the stored signal to the identified second portion of the stored signal to objectively determine whether the subject has tinnitus.   
   
   
       11 . The method of  claim 10  wherein said receiving comprises receiving a plurality of input signals, each input signal representing an electrical response of the subject's central nervous system to the sound pattern, and further comprising computing an average input signal for the received plurality of input signals, and wherein said storing the input signal comprises storing the computed average input signal. 
   
   
       12 . The method of  claim 10  wherein the background acoustic signal precedes and follows the audible silence in the sound pattern, and wherein identifying a second portion of the stored signal representing the electrical response of the subject's central nervous system to the audible silence includes identifying a magnitude of the electrical response measured after a pre-defined period following the subject's initial exposure to the audible silence in the sound pattern. 
   
   
       13 . The method of  claim 10  wherein said comparing includes computing a gain between the identified first portion of the stored signal and the identified second portion of the stored signal. 
   
   
       14 . The method of  claim 10  further comprising rendering a report for a user, said report indicating that the subject has tinnitus when the computed gain is greater than or equal to a pre-defined threshold value, said report indicating that subject does not have tinnitus when the computed gain is less than the pre-defined threshold value. 
   
   
       15 . An apparatus for objectively identifying an acoustic characteristic of tinnitus of a human or animal subject comprising:
 a transducer for creating a sound pattern and exposing the sound pattern to the subject, said sound pattern including a background acoustic signal having a selected acoustic characteristic and an audible silence, the background acoustic signal preceding the audible silence;   an electroencephalogram (EEG) sensing device to measure an electrical response of the subject's central nervous system to the sound pattern; and   a controller for determining whether the subject has tinnitus characterized by an acoustic characteristic similar to the selected acoustic characteristic as a function of the electrical response of the subject's central nervous system measured by the EEG sensing device while the subject was exposed to the background acoustic signal compared with the electrical response of the subject's central nervous system measured by the EEG sensing device while the subject was exposed to the audible silence.   
   
   
       16 . The apparatus of  claim 15  wherein the selected acoustic characteristic of the background acoustic signal includes a value for one or more of the following parameters of the background acoustic signal: frequency, amplitude, and waveform. 
   
   
       17 . The apparatus of  claim 15  wherein the controller is further configured to adjust the selected acoustic characteristic when the subject is determined not to have tinnitus characterized by an acoustic characteristic similar to the selected acoustic characteristic. 
   
   
       18 . The apparatus of  claim 15  further comprising a storage memory for storing data representing a measured electrical response of the subject's central nervous system to another sound pattern, the other sound pattern including another background acoustic signal having another selected acoustic characteristic and an audible silence, the other background acoustic signal preceding and following the audible silence, wherein said controller is further configured to determine whether the subject has tinnitus characterized by an acoustic characteristic similar to the selected acoustic characteristic as a function of the stored data. 
   
   
       19 . The apparatus of  claim 15  further comprising a user interface in communication with the transducer for receiving an input from a user to select the selected acoustic characteristic of the background acoustic signal. 
   
   
       20 . The apparatus of  claim 15  wherein said transducer is configured for repeatedly exposing the sound pattern to the subject, and wherein said EEG sensing device is configured to measure the electrical response of the subject's central nervous system to the sound pattern each time the sound pattern is exposed to the subject, and wherein said controller is configured to compute an average electrical response of the subject's central nervous system from each of the electrical responses measured by the EEG sensing device, said average electrical response including a first portion representing the average electrical response of the subject's central nervous system to the background acoustic signal and a second portion representing the average electrical response of the subject's central nervous system to the audible silence, and wherein said controller is further configured to determine whether the subject has tinnitus characterized by an acoustic characteristic similar to the selected acoustic characteristic as a function of the first portion of the computed average electrical response compared with the second portion of the computed average electrical response.