Hearing instrument and method of identifying an output transducer of a hearing instrument

1. A method for identifying an output transducer of a hearing instrument, the method comprising:

applying a pseudo-random signal to the output transducer;

receiving a response signal indicative of the impedance of the output transducer;

computing a cross-correlation of the response signal and the pseudo-random signal;

computing a Fourier transform of the computed cross-correlation;

comparing the computed Fourier transform with one or more reference models; and

identifying the output transducer based on the comparison.

2. The method of claim 1 , wherein the output transducer is a receiver in the ear (RITE) type output transducer.

3. The method of claim 1 further comprising:

generating the pseudo-random signal using a linear feedback shift register.

4. The method of claim 1 further comprising:

applying a plurality of pseudo-random signals to the output transducer;

receiving a plurality of response signals corresponding to the plurality of pseudo-random signals; and

selecting one of the plurality of response signals and a corresponding one of the pseudo-random signal for computing the cross-correlation.

5. The method of claim 1 further comprising:

applying a plurality of instances of the pseudo-random signal to the output transducer;

receiving a plurality of response signals corresponding to the plurality of instances of the pseudo-random signal; and

computing the response signal as a mean of the plurality of response signals.

6. The method of claim 1 further comprising:

recording the response signal in the hearing instrument.

7. The method of claim 1 , wherein the one or more reference models comprise impedance versus frequency characteristics of one or more known output transducers.

8. A hearing instrument comprising:

an output transducer; and

a signal processor configured to:

apply a pseudo-random signal to the output transducer;

receive a response signal indicative of the impedance of the output transducer;

compute a cross-correlation of the response signal and the pseudo-random signal;

compute a Fourier transform of the computed cross-correlation;

compare the computed Fourier transform with one or more reference models; and

identify the output transducer based on the comparison.

9. The hearing instrument of claim 8 , wherein the hearing instrument is a receiver in the ear (RITE) type instrument.

10. The hearing instrument of claim 8 , wherein the signal processor further comprises a linear feedback shift register to generate the pseudo-random signal.

11. The hearing instrument of claim 8 , wherein the signal processor is further configured to:

apply a plurality of pseudo-random signals to the output transducer;

receive a plurality of response signals corresponding to the plurality of pseudo-random signals; and

select one of the plurality of response signals and a corresponding one of the pseudo-random signal for computing the cross-correlation.

12. The hearing instrument of claim 8 , wherein the signal processor is further configured to:

apply a plurality of instances of the pseudo-random signal to the output transducer;

receive a plurality of response signals corresponding to the plurality of instances of the pseudo-random signal; and

compute the response signal as a mean of the plurality of response signals.

13. The hearing instrument of claim 8 further comprising a memory configured to:

record the response signal; and

store the one or more reference models.

14. The hearing instrument of claim 8 further comprising:

an analog to digital converter;

a sense resistor having a first lead and a second lead, wherein the first lead is electrically coupled to an input of the analog to digital converter, and the second lead is electrically coupled to a ground terminal of the signal processor; and

a switching switch unit configured to:

disconnect a negative lead of the output transducer from a negative operating output pin of the signal processor;

place the negative operating output pin of the signal processor in a high impedance state; and

connect the negative lead of the output transducer to the input of the analog to digital converter and the first lead of the sense resistor.

15. The hearing instrument of claim 8 further comprising a transducer identification output configured to produce one or more of an audible signal, a visible signal, or an electrical signal indicating the type of output transducer connected, based on the identification.

16. The hearing instrument of claim 8 further comprising a user interface allowing an initiation of said identification of the output transducer and/or a presentation of the result of the identification of the output transducer.

17. The hearing instrument of claim 16 wherein the user interface is implemented on a remote control device or a SmartPhone.

18. The hearing instrument of claim 8 wherein the output transducer or a cable or connector for connecting the output transducer to the signal processor comprises an identification resistor having a resistance indicative of the type of output transducer and wherein the hearing instrument is configured to measure said resistance and compare it to a number of predefined resistances indicative of respective different types of output transducers and to identify the type of output transducer presently connected to the hearing instrument based on the comparison.

19. The hearing instrument of claim 8 configured to perform a self diagnosis including performing the identification of the output transducer at each power on of the hearing instrument and/or on demand of a user.

20. The hearing instrument of claim 8 configured to detect mechanical damages in the output transducer based on the comparison of the computed Fourier transform with the one or more reference models.