Acoustic otoscope

Abstract

An acoustic otoscope generates volume change excitations of either a trapezoidal or sinusoidal waveforms which are coupled into a sealed ear canal using a speculum tip. The change in volume results in a pressure change, for which a pressure measurement is taken during the volume change excitation interval. In one example, a trapezoidal time-domain volume change is presented, and a pressure measurement waveform is stored, the pressure measurement waveform thereafter examined to find a change of slope point in time, after which the pressure measurement waveform is scaled to be equal to the volume change waveform at that same point in time, a difference between scaled pressure measurement and volume excitation is formed, and examined for peak value prior to the earlier determined change in slope point in time.

1 . (canceled) 
     
     
         2 . A method of characterizing an ear, the method comprising:
 generating, with an excitation source, dynamic volume or pressure in an ear canal with a speculum tip coupled to the ear canal, the dynamic volume or pressure being based on an input waveform;   receiving one or more pressure sensor measurements from a pressure sensor coupled to the speculum tip coupled to the ear canal, the one or more pressure sensor measurements comprising an output waveform;   comparing the input waveform for the dynamic volume or pressure with the output waveform; and   outputting an effusion metric based at least in part on the comparison of the input waveform with the output waveform.   
     
     
         3 . The method of  claim 2 , wherein outputting the effusion metric comprises generating one or more difference values from subtracting a scaled output waveform of the pressure measurement from the input waveform of the excitation source. 
     
     
         4 . The method of  claim 3 , wherein outputting the effusion metric further comprises deriving the effusion metric from the one or more difference values, and wherein the one or more difference values has an elevated amplitude following a step change in pressure or volume compared to a subsequent difference value. 
     
     
         5 . The method of  claim 3 , wherein outputting the effusion metric further comprises deriving the effusion metric from the one or more difference values, and wherein the one or more difference values has an elevated amplitude for a low frequency pressure or volume excitation compared to an amplitude for a high frequency pressure or volume excitation. 
     
     
         6 . The method of  claim 3 , wherein the one or more difference values is averaged over at least 4 acquisition cycles. 
     
     
         7 . The method of  claim 3 , wherein the scaled output waveform of the pressure measurement comprises a scaling factor, and wherein the one or more pressure measurements has a mid-point value substantially equal to a mid-point input value of the input waveform of the excitation source. 
     
     
         8 . The method of  claim 2 , wherein the input waveform of the excitation source is trapezoidal. 
     
     
         9 . The method of  claim 2 , wherein the input waveform of the excitation source is sinusoidal. 
     
     
         10 . The method of  claim 9 , wherein the sinusoidal input waveform of the excitation source and the pressure measurement output waveform are acquired over several frequencies to determine a corner frequency. 
     
     
         11 . The method of  claim 10 , wherein outputting the effusion metric comprises comparing the corner frequency to a threshold frequency corresponding to one or more of a normal tympanic membrane, a viral fluid adjacent to a tympanic membrane, or a mucoid fluid adjacent to a tympanic membrane. 
     
     
         12 . The method of  claim 2 , wherein the excitation source comprises:
 a moveable diaphragm,   a moveable piston, or   a source of differential pressure coupled to the speculum tip with a hose.   
     
     
         13 . The method of  claim 2 , wherein the excitation source comprises a diaphragm or piston enclosed in the speculum tip or a mount for the speculum tip. 
     
     
         14 . The method of  claim 2 , wherein the excitation source is coupled to a source of greater or lower air pressure through one or more valves. 
     
     
         15 . A method of characterizing an ear, the method comprising:
 modulating pressure within an ear canal with an excitation source coupled to a speculum tip inserted within the ear canal, the speculum tip forming a seal when inserted into the ear canal;   measuring the pressure within the ear canal with a pressure sensor coupled to the speculum tip;   generating an excitation source input waveform, wherein the pressure within the ear canal is modulated based on the generated excitation source input waveform;   receiving a pressure measurement output waveform based on the measured pressure;   determining an effect of the excitation source input waveform on the pressure measurement output waveform;   comparing the pressure measurement output waveform with the excitation source input waveform; and   generating an effusion metric based at least in part on a comparison of the excitation source input waveform with the pressure measurement output waveform.   
     
     
         16 . The method of  claim 15 , wherein the excitation source is configured to cause a volume change or a pressure change within the ear canal. 
     
     
         17 . The method of  claim 15 , wherein the excitation source is a moving diaphragm. 
     
     
         18 . The method of  claim 15 , further comprising, after a monotonic pressure sequence of a first threshold and a second threshold, using the effusion metric to identify a non-diagnostic speculum tip leak when:
 (i) a transfer function for the pressure measurement output waveform to the excitation source input waveform is below the first threshold;   (ii) a high frequency transfer function for the pressure measurement output waveform to the excitation source input waveform is below the second threshold;   (iii) a negative pressure response is detected when the excitation source is a volume modulating piston or diaphragm which is returned to an original position; or   (iv) a pressure measurement change is not detected in response to the excitation source waveform.   
     
     
         19 . The method of  claim 15 , wherein the excitation source input waveform is a sinusoidal waveform and the effusion metric is based on a corner frequency in a frequency response function
 ΔP(f) / ΔV(f) where:
 ΔP(f) is a pressure amplitude for a plurality of discrete frequencies; 
 ΔV(f) is a volume excitation amplitude for a plurality of discrete frequencies; and 
 the corner frequency is a frequency f for which the frequency response function is less than 1/√ { square root over (2)} of a value at a higher frequency. 
   
     
     
         20 . The method of  claim 15 , wherein the excitation source input waveform is a trapezoidal waveform, wherein the effusion metric is based on a difference waveform, wherein the difference waveform is a difference between the excitation source input waveform and the pressure measurement output waveform, and wherein the pressure output measurement waveform is scaled to a midpoint of the excitation source input waveform. 
     
     
         21 . The method of  claim 20 , wherein the midpoint is an earliest of a point in time where a slope of the pressure measurement output waveform changes to ¼ or less of its initial value or a half interval point, whichever occurs sooner. 
     
     
         22 . The method of  claim 20 , wherein the effusion metric is based on a maximum amplitude of the difference waveform before the midpoint.