ADAPTIVE CANCELLATION SYSTEM FOR IMPLANTABLE HEARING INSTRUMENTS

• US 20080132750A1
• Filed: 11/30/2006
• Published: 06/05/2008
• Est. Priority Date: 01/11/2005
• Status: Active Grant

• Current Assignee: Otologics, LLC
• Original Assignee: Otologics, LLC
• Inventors: Miller, Scott Allan
• Granted Patent: US 8,096,937 B2
• Time in Patent Office: Days
• US Class Current: 600/25
• CPC Class Codes: H04R 25/453 electronically
• CPC Class Codes: H04R 25/606 acting directly on the eardrum, the ossicles or the skull, e.g. mastoid, tooth, maxillary or mandibular bone, or mechanically stimulating the cochlea, e.g. at the oval window

Abstract

The invention is directed to an implanted microphone having reduced sensitivity to vibration. In this regard, the microphone differentiates between the desirable and undesirable vibration by utilizing at least one motion sensor to produce a motion signal when an implanted microphone is in motion. This motion signal is used to yield a microphone output signal that is less vibration sensitive. In a first arrangement, the motion signal may be processed with an output of the implantable microphone transducer to provide an audio signal that is less vibration-sensitive than the microphone output alone. Specifically, the motion signal may be scaled to match the motion component of the microphone output such that upon removal of the motion signal from the microphone output, the remaining signal is an acoustic signal.

Claims

1. A method for use with an implantable hearing instrument, comprising:

generating a first system model of a first relationship of output signals of an implantable microphone and a motion sensor in response to a first operating environment;

generating a second system model of a second relationship of output signals of said implantable microphone and said motion sensor in response to a second operating environment, wherein said first and second operating environments are different; and

using said first and second system models, generating a variable system model of relationships of output signals of said implantable microphone and said motion sensor, wherein said variable system model is at least partially dependent upon a variable operating environment of said hearing instrument.

2. The method of claim 1, wherein said variable operating environment comprises a latent parameter associated with said variable operating environment.

3. The method of claim 2, further comprising:

interactively identifying a value associated with said latent parameter.

4. The method of claim 1, further comprising:

identifying a value associated with said variable operating environment; and

based on said value, utilizing said variable system model to alter at least a first characteristic of subsequent output signals of said motion sensor and generate altered output signals.

5. The method of claim 4, further comprising:

combining said altered output signals with corresponding output signals of said implantable microphone.

6. The method of claim 5, wherein combining comprises subtracting said altered output signals from said corresponding output signals of said implantable microphone.

7. The method of claim 1, wherein generating said first and second system models comprises generating first and second mathematical functions approximating said first and second relationships, respectively.

8. The method of claim 7, wherein generating said variable system model comprises:

identifying two or more parameters associated with each of said first and second mathematical functions that vary based on said first and second operating conditions; and

reducing a dimensionality of said parameters to define a range of variance associated with said first and second operating conditions.

9. The method of claim 8, further comprising:

identifying dependency relationships between corresponding parameters of said functions and said range of variance; and

utilizing said dependency relationships to generate filter coefficients for said variable system model, wherein each said filter coefficient is dependent upon said range of variance.

10. The method of claim 1, wherein generating first and second system models in response to first and second operating environments comprises generating said first and second systems models in response to first and second different postures of a user of said implantable hearing instrument.

11. The method of claim 1, further comprising:

generating a plurality of system models associated with a plurality of operating conditions; and

using said plurality of system models to generate said variable system model.

12. A method for use with an implantable hearing instrument, comprising:

generating a plurality of system models defining relationships of corresponding outputs of an implantable microphone and a motion sensor, wherein said plurality of system models are associated with a corresponding plurality of different operating environments for said hearing instrument;

identifying at least one parameter of said system models that varies between different system models;

fitting a function to a set of values corresponding to said at least one parameter that varies between different system models, wherein said function defines a range of variance for said plurality of operating environments;

utilizing said function and said system models to generate an variable system model that is dependent on an operating environment variable associated with said range of variance.

13. The method of claim 12, wherein said different operating environments each comprise a different posture of the user of the hearing instrument.

14. The method of claim 13, wherein said operating environment variable comprises a posture dependent variable.

15. The method of claim 12, wherein identifying comprises identifying at least two parameters for each said system model, wherein said at least two parameters vary between system models.

16. The method of claim 15, wherein fitting a function comprises:

performing a principal component reduction on values associated with said at least two parameters.

17. The method of claim 12, wherein utilizing said function further comprises:

identifying relationships of said system models to said function; and

utilizing said relationships to generate filter coefficients for said variable system model, wherein said filter coefficients are dependent on said operating environment variable.

18. The method of claim 17, further comprising:

generating an estimated value of said operating environment variable;

based on said estimated value, utilizing said variable system model to adjust at least a portion of an output of a motion sensor to generate an adjusted output; and

removing said adjusted output from an output of an implantable microphone .

19. The method of claim 18, further comprising:

iteratively adjusting said estimated value to minimize a residual associated with the removing of said adjusted output from said output of said implantable microphone.

20. A method for use with an implantable hearing instrument, comprising:

providing an adaptive filter operative to model relationships of outputs of an implantable microphone and a motion sensor, wherein filter coefficients of said adaptive filter are dependent upon a latent variable associated with variable operating conditions of said implantable hearing instrument;

receiving outputs from an implantable microphone and a motion sensor;

generating an estimate of said latent variable, wherein said filter coefficients are adjusted based on said estimate of said latent variable;

filtering said motion output to produce a filtered motion output; and

removing said filtered motion output from said microphone output to produce a cancelled output.

21. The method of claim 20, further comprising:

generating a plurality of estimates of said latent variable, wherein said filter coefficients are adjusted to each of said plurality of estimates;

filtering said motion output for each estimate of said latent variable to generate a plurality of filtered motion outputs;

removing each of said plurality of filtered outputs from said microphone output to produce a plurality of cancelled microphone outputs.

22. The method of claim 20, further comprising:

selecting one of said plurality of cancelled microphone outputs for subsequent processing.

23. The method of claim 22, wherein selecting comprises identifying one of said plurality of cancelled microphone outputs having the lowest residual energy.

24. A method for use with an implantable hearing instrument, comprising:

providing first and second adaptive filters operative to filter the output of a motion sensor to substantially match the output of an implantable microphone, wherein said first and second filters are identical and wherein filter coefficients of each said adaptive filter are dependent upon a variable associated with operating conditions of said implantable hearing instrument;

receiving outputs from an implantable microphone and a motion sensor;

generating an estimate of said variable;

first filtering said motion output using said first adaptive filter to produce a first filtered motion output, wherein said first adaptive filter utilizes filter coefficients generated based on said estimate of said variable;

second filtering said motion output using said second adaptive filter to produce a second filtered motion output, wherein said second adaptive filter utilizes filter coefficients that are a predetermined value different than said estimate of said variable;

removing said first and second filtered outputs from said output of said implantable microphone to generate first and second cancelled signals; and

adjusting said estimate of said variable based on a comparison of said first and second cancelled signals.

25. The method of claim 24, wherein said variable comprises a latent variable.

26. The method of claim 24, further comprising repeating said first filtering, second filtering, removing and adjusting steps until energies of said first and second cancelled signals are substantially equal.

27. The method of claim 24, further comprising:

selecting one of said first and second cancelled signals for subsequent processing.

28. The method of claim 24, further comprising:

averaging said first and second cancelled signals to generate an averaged cancelled signal;

wherein said averaged cancelled signal is utilized for subsequent processing.

29. The method of claim 24, wherein receiving outputs from an implantable microphone and a motion sensor, further comprises:

splitting said outputs in to first and second channels, wherein said first filtering is performed on said first channel and said second filtering is performed on said second channel.

30. The method of claim 24, wherein said first filtering and second filtering are performed concurrently.

31. A system for use with an implantable hearing instrument, comprising:

an implantable microphone operative to subcutaneously receive sound and generate a microphone output signal;

a microphone operative to receive sound and generate a microphone output, said microphone being adapted for subcutaneous positioning;

a motion sensor for generating a motion signal indicative of motion of said microphone;

a first adaptive filter operative to filter the output of said motion sensor to correspond with the output of said implantable microphone to motion, wherein filter coefficients of said first adaptive filter are dependent upon a variable associated with operating conditions of said implantable hearing instrument;

a first summation device for combining said microphone output and said filtered motion signal to generate a first cancelled signal;

a second adaptive filter operative to filter the output of said motion sensor to substantially model the output of said implantable microphone to motion, wherein said first and second filters are identical and wherein filter coefficients of each said adaptive filter are dependent upon a variable associated with operating conditions of said implantable hearing instrument;

a second digital filter adapted to receive said motion sensor and generate a feedback signal that models a response of said microphone to operation of said implantable auditory stimulation device;

a second summation device for combining said microphone output and said feedback signal to generate a second compensated microphone signal; and

a controller operative to select at least a portion of one of said first and second compensated microphone signals for at least one frequency band and provide such selected portions to a signal processor for use in generating drive signals for actuating said implantable auditory stimulation device.

a motion sensor operative to generate a motion sensor output indicative of motion;

a first adaptive filter for modeling said motion sensor output to said microphone output, wherein coefficients of said adaptive filter are dependent upon a variable associated with operating conditions of said implantable hearing instrument.