Middle ear vibration sensor using multiple transducers

Abstract

A hearing assistance system includes multiple middle ear transducers for sensing vibrations of an ossicle or other auditory element. The hearing assistance system is configured to accommodate an unknown or variable direction of the vibration. Two transducers are arranged to transduce nonidentical directional components of the vibration into electrical signals which are then combined. The combined electrical signal is approximately independent of the direction of the vibration, or has improved frequency response, or has an amplitude that is approximately independent of the direction of the vibration. The combined electrical signal may result from a square root of sum-of-squares, sum of individually filtered signals, differentiation, or other techniques. The hearing assistance system analogously accommodates three dimensional variability of the direction of vibration using three middle ear transducers.

What is claimed is:  
     
         1 . A method of transducing a mechanical vibration of an auditory element into at least one electrical signal, the method comprising the steps of: 
 positioning a first input transducer to transduce a first directional component of the mechanical vibration into a first electrical signal; and    positioning a second input transducer to transduce a second directional component of the mechanical vibration into a second electrical signal, wherein the first and second directional components of the mechanical vibration are nonidentical.    
     
     
         2 . The method of    claim 1   , wherein the first and second input transducers are each coupled to the auditory element.  
     
     
         3 . The method of    claim 1   , wherein the steps of positioning the first and second input transducers provide a predetermined angle between the first and second directional components of the mechanical vibration.  
     
     
         4 . The method of    claim 3   , wherein the first and second directional components of the mechanical vibration are approximately orthogonal.  
     
     
         5 . The method of    claim 1   , wherein the steps of positioning the first and second input transducers provide a predetermined spatial relationship therebetween.  
     
     
         6 . The method of    claim 1   , wherein at least one of the first and second transducers includes at least one piezoelectric bimorph transducer element.  
     
     
         7 . The method of    claim 1   , wherein at least one of the first and second transducers includes a piezoelectric film transducer element.  
     
     
         8 . The method of    claim 1   , wherein at least one of the first and second transducers includes an electromagnetic transducer.  
     
     
         9 . The method of    claim 1   , wherein at least one of the first and second transducers includes an accelerometer.  
     
     
         10 . The method of    claim 1   , wherein at least one of the first and second transducers includes a capacitive transducer.  
     
     
         11 . The method of    claim 1   , wherein the auditory element is part of an ossicular chain.  
     
     
         12 . The method of    claim 1   , further comprising the step of positioning a third input transducer to transduce a third directional component of the mechanical vibration into a third electrical signal, wherein the first, second, and third directional components of the mechanical vibration are nonidentical and linearly independent.  
     
     
         13 . The method of    claim 12   , wherein the steps of positioning the first, second, and third input transducers provide a predetermined spatial relationship therebetween.  
     
     
         14 . The method of    claim 12   , wherein the steps of positioning the first, second, and third input transducers provide approximately orthogonal reception of the first, second, and third directional components of the mechanical vibration.  
     
     
         15 . The method of    claim 12   , wherein the third input transducer is coupled to the auditory element.  
     
     
         16 . The method of    claim 12   , further comprising the step of combining the first, second, and third electrical signals to provide a resulting combined electrical signal.  
     
     
         17 . The method of    claim 1   , further comprising the step of combining the first and second electrical signals to provide a resulting combined electrical signal.  
     
     
         18 . The method of    claim 17   , wherein the combined electrical signal is approximately independent of the direction of the mechanical vibration.  
     
     
         19 . The method of    claim 17   , wherein the combined electrical signal is approximately compensated for frequency dependence of the direction of the mechanical vibration.  
     
     
         20 . The method of    claim 17   , wherein the step of combining the first and second electrical signals includes the steps of: 
 squaring each of the first and second electrical signals to provide resulting first and second squared electrical signals;    summing each of the first and second squared electrical signals to provide a resulting sum-of-squares signal; and    taking the square root of the sum-of-squares signal to provide a resulting combined electrical signal.    
     
     
         21 . The method of    claim 17   , wherein the step of combining the first and second electrical signals includes the steps of: 
 filtering each of the first and second electrical signals to provide resulting first and second filtered electrical signals; and    summing each of the first and second filtered electrical signals to provide a resulting combined electrical signal.    
     
     
         22 . The method of    claim 21   , wherein the step of filtering each of the first and second electrical signals includes the steps of: 
 low-pass filtering the first electrical signal to provide the resulting first filtered electrical signal; and    high-pass filtering the second electrical signal to provide the resulting second filtered electrical signal.    
     
     
         23 . The method of    claim 17   , wherein the step of combining the first and second electrical signals includes the steps of: 
 differentiating the second electrical signal to provide a resulting second differentiated electrical signal; and    summing the first electrical signal and the second differentiated electrical signal to provide a resulting combined electrical signal.    
     
     
         24 . The method of    claim 1   , wherein the first and second input transducers have different frequency response characteristics.  
     
     
         25 . A middle-ear implantable sensor for transducing a mechanical vibration of an auditory element into an electrical signal, the sensor comprising: 
 a first input transducer, proportioned for transducing a first directional component of the mechanical vibration into a first electrical signal; and    a second input transducer, proportioned for transducing a second directional component of the mechanical vibration into a second electrical signal, wherein the first and second directional components of the mechanical vibration are nonidentical.    
     
     
         26 . The sensor of    claim 25   , wherein the first and second input transducers are each proportioned for coupling to the auditory element.  
     
     
         27 . The sensor of    claim 25   , wherein the first and second input transducers are arranged with a predetermined spatial relationship therebetween.  
     
     
         28 . The sensor of    claim 25   , wherein the first and second input transducers are arranged to provide a predetermined angle between the first and second directional components of the mechanical vibration.  
     
     
         29 . The sensor of    claim 28   , wherein the first and second directional components of the mechanical vibration are substantially orthogonal.  
     
     
         30 . The sensor of    claim 25   , wherein at least one of the first and second transducers includes a piezoelectric bimorph transducer element.  
     
     
         31 . The sensor of    claim 25   , wherein at least one of the first and second transducers includes a piezoelectric film transducer element.  
     
     
         32 . The sensor of    claim 25   , wherein at least one of the first and second transducers includes an electromagnetic transducer.  
     
     
         33 . The sensor of    claim 25   , wherein at least one of the first and second transducers includes an accelerometer.  
     
     
         34 . The sensor of    claim 25   , wherein at least one of the first and second transducers includes a capacitive transducer.  
     
     
         35 . The sensor of    claim 25   , wherein the auditory element is part of an ossicular chain.  
     
     
         36 . The sensor of    claim 35   , wherein t he auditory element is a malleus.  
     
     
         37 . The sensor of    claim 25   , further comprising a third input transducer, proportioned for transducing a third directional component of the mechanical vibration into a third electrical signal, wherein the first, second, and third directional components are nonidentical and linearly independent.  
     
     
         38 . The sensor of    claim 37   , wherein the first, second, and third input transducers are arranged with predetermined angular spacings therebetween.  
     
     
         39 . The sensor of    claim 37   , wherein the first, second, and third input transducers are arranged to provide predetermined angles between the first, second, and third directional components of the mechanical vibration.  
     
     
         40 . The sensor of    claim 39   , wherein the first, second, and third input transducers are arranged to provide approximately orthogonal reception of the first, second, and third directional components of the mechanical vibration.  
     
     
         41 . The sensor of    claim 39   , wherein the third input transducer is proportioned for coupling to the auditory element.  
     
     
         42 . The sensor of    claim 37   , further comprising a carrier that carries the first, second, and third input transducers.  
     
     
         43 . The sensor of    claim 42   , wherein the first, second, and third input transducers coupled to the carrier to provide predetermined angles between the first, second, and third directional components of the mechanical vibration.  
     
     
         44 . The sensor of    claim 43   , wherein the first, second, and third directional components of the mechanical vibration are approximately orthogonal.  
     
     
         45 . The sensor of    claim 25   , further comprising a carrier, carrying the first and second input transducers in a predetermined spatial relationship therebetween.  
     
     
         46 . The sensor of    claim 45   , wherein the first and second input transducers are coupled to the carrier to provide a predetermined angle between the first and second directional components of the mechanical vibration.  
     
     
         47 . The sensor of    claim 46   , wherein the first and second directional components of the mechanical vibration are approximately orthogonal.  
     
     
         48 . The sensor of    claim 45   , wherein at least one of the first and second input transducer is adjustably coupled to the carrier.  
     
     
         49 . The sensor of    claim 25   , wherein the first and second input transducers have different frequency response characteristics.  
     
     
         50 . An at least partially implantable hearing assistance system, comprising: 
 a sensor for transducing a mechanical vibration of an auditory element into an electrical signal, the sensor including: 
 a first input transducer, proportioned for transducing a first directional component of the mechanical vibration into a first electrical signal; and  
 a second input transducer, proportioned for transducing a second directional component of the mechanical vibration into a second electrical signal, wherein the first and second directional components of the mechanical vibration are nonidentical; and  
   an electronics unit, coupled to the sensor for receiving the first and second electrical signals therefrom.    
     
     
         51 . The system of    claim 50   , wherein the electronics unit comprises: 
 a first squaring circuit, receiving the first electrical signal and providing a first squared electrical signal in response thereto;    a second squaring circuit, receiving the second electrical signal and providing a second squared electrical signal in response thereto;    a summer, receiving each of the first and second squared electrical signals and providing a resulting sum-of-squares electrical signal in response thereto; and    a square root circuit, receiving the sum-of-squares electrical signal and providing a combined electrical signal in response thereto.    
     
     
         52 . The system of    claim 51   , wherein the electronics unit comprises: 
 a first filter, receiving the first electrical signal and providing a first filtered signal in response thereto;    a second filter, receiving the second electrical signal and providing a second filtered signal in response thereto; and    a summer, receiving the first and second filtered electrical signals, and providing a combined electrical signal in response thereto.    
     
     
         53 . The system of    claim 52   , wherein the first filter includes a low pass filter and the second filter includes a high-pass filter.  
     
     
         54 . The system of    claim 50   , wherein the electronics unit comprises: 
 a differentiator, receiving the second electrical signal and providing a second differentiated electrical signal in response thereto; and    a summer, receiving each of the first electrical signal and the second differentiated electrical signal, and providing a combined electrical signal in response thereto.    
     
     
         55 . The system of    claim 50   , wherein the electronics unit provides a combined electrical signal in response to the first and second electrical signals, and the combined electrical signal is approximately independent of the direction of the mechanical vibration of the auditory element.  
     
     
         56 . The system of    claim 50   , wherein the electronics unit provides a combined electrical signal in response to the first and second electrical signals, and the combined electrical signal is approximately compensated for frequency dependence of the direction of the mechanical vibration.  
     
     
         57 . The system of    claim 50   , further comprising a programmer adapted to be communicatively coupled to the electronics unit.  
     
     
         58 . The system of    claim 57   , wherein the programmer and electronics unit are adapted to be inductively coupled.