Objective determination of acoustic prescriptions

1. A method, comprising:

delivering one or more sets of acoustic stimulation signals to an inner ear of a recipient of a hearing prosthesis;

obtaining, in response to the one or more sets of acoustic stimulation signals, at least one measure of outer hair cell function from a tonotopic region of the inner ear of the recipient;

obtaining, in response to the one or more sets of acoustic stimulation signals, at least one measure of auditory nerve function from the tonotopic region of the inner ear of the recipient;

comparing a value associated with the at least one measure of auditory nerve function to a value associated with the at least one measure of outer hair cell function;

identifying a dead region of the inner ear based on a deviation between the value associated with the at least one measure of auditory nerve function and the value associated with the at least one measure of outer hair cell function; and

generating an acoustic prescription for the recipient that excludes fitting frequencies corresponding to the dead region.

2. The method of claim 1 , wherein comparing a value associated with the at least one measure of auditory nerve function to a value associated with the at least one measure of outer hair cell function comprises:

determining whether the at least one measure of auditory nerve function differs from an expected measure of auditory nerve function for the tonotopic region the inner ear;

determining whether the at least one measure of outer hair cell function differs from an expected measure of outer hair cell function for the tonotopic region the inner ear; and

analyzing any differences between the at least one measure of auditory nerve function and the expected measure of auditory nerve function relative to any differences between the at least one measure of outer hair cell function and the expected measure of outer hair cell function.

3. The method of claim 1 , wherein obtaining the at least one measure of outer hair cell function from the tonotopic region of the inner ear of the recipient comprises:

obtaining at least one cochlear microphonic from the tonotopic region of the inner ear of the recipient.

4. The method of claim 1 , wherein obtaining the at least one measure of auditory nerve function from the tonotopic region of the inner ear of the recipient comprises:

obtaining at least one auditory nerve neurophonic from the tonotopic region of the inner ear of the recipient.

5. The method of claim 1 , wherein comparing a value associated with the at least one measure of auditory nerve function to a value associated with the at least one measure of outer hair cell function comprises:

analyzing the at least one measure of auditory nerve function relative to the at least one measure of outer hair cell function to determine whether the tonotopic region of the inner ear has a physiological abnormality.

6. The method of claim 5 , further comprising:

identifying a presence of a physiological abnormality at the tonotopic region; and

identifying a type of the physiological abnormality present at the tonotopic region.

7. The method of claim 1 , wherein comparing a value associated with the at least one measure of auditory nerve function to a value associated with the at least one measure of outer hair cell function comprises:

analyzing the at least one measure of auditory nerve function relative to the at least one measure of outer hair cell function to determine whether the tonotopic region of the inner ear is functioning, in response to the one or more sets of acoustic stimulation signals, in accordance with at least one predetermined expectation.

8. The method of claim 1 , further comprising:

determining, based on the comparing of the value associated with the at least one measure of auditory nerve function to the value associated with the at least one measure of outer hair cell function, at least one input/output for the tonotopic region of the inner ear.

9. The method of claim 1 , further comprising:

determining, based on the comparing of the value associated with the at least one measure of auditory nerve function to the value associated with the at least one measure of outer hair cell function, one or more gain functions for the tonotopic region of the inner ear.

10. The method of claim 9 , further comprising:

obtaining an audiogram generated for the inner ear of the recipient; and

determining the one or more gain functions based on the comparing of the value associated with of the at least one measure of auditory nerve function to the value associated with the at least one measure of outer hair cell function and based on the audiogram generated for the inner ear of the recipient.

11. The method of claim 1 , wherein delivering one or more sets of acoustic stimulation signals to an inner ear of a recipient of a hearing prosthesis:

delivering acoustic stimulation signals at a selected and substantially constant frequency while incrementally adjusting an amplitude of the acoustic stimulation signals.

12. An apparatus, comprising:

a memory; and

one or more processors configured to:

obtain at least one cochlear microphonic evoked at a tonotopic region of an inner ear of a recipient of a hearing prosthesis,

obtain at least one auditory nerve neurophonic evoked from the tonotopic region of the inner ear of the recipient,

determine whether the at least one auditory nerve neurophonic differs from an expected auditory nerve neurophonic for the tonotopic region the inner ear;

determine whether the at least one cochlear microphonic differs from an expected cochlear microphonic for the tonotopic region the inner ear;

correlate any differences between the at least one auditory nerve neurophonic and the expected auditory nerve neurophonic with any differences between the at least one cochlear microphonic and the expected cochlear microphonic;

identify a dead region of the inner ear based on a deviation between the at least one auditory nerve neurophonic and the at least one cochlear microphonic; and

generating an acoustic prescription for the recipient that excludes fitting frequencies corresponding to the dead region.

13. The apparatus of claim 12 , wherein to correlate any differences between the at least one auditory nerve neurophonic and the expected auditory nerve neurophonic with any differences between the at least one cochlear microphonic and the expected cochlear microphonic, the one or more processors are configured to:

analyze any differences between the at least one auditory nerve neurophonic and the expected auditory nerve neurophonic relative to any differences between the at least one cochlear microphonic and the expected cochlear microphonic to determine whether the tonotopic region of the inner ear has a physiological abnormality.

14. The apparatus of claim 12 , wherein the one or more processors are further configured to:

determine, based on the correlating of any differences between the at least one auditory nerve neurophonic and the expected auditory nerve neurophonic with any differences between the at least one cochlear microphonic and the expected cochlear microphonic, at least one input/output for the tonotopic region of the inner ear.

15. The apparatus of claim 12 , wherein the one or more processors are further configured to:

determine, based on the correlating of any differences between the at least one auditory nerve neurophonic and the expected auditory nerve neurophonic with any differences between the at least one cochlear microphonic and the expected cochlear microphonic, one or more gain functions for the tonotopic region of the inner ear.

16. The apparatus of claim 15 , wherein the one or more processors are further configured to:

obtain an audiogram generated for the inner ear of the recipient; and

determine the one or more gain functions based on the correlating of any differences between the at least one auditory nerve neurophonic and the expected auditory nerve neurophonic with any differences between the at least one cochlear microphonic and the expected cochlear microphonic and based on the audiogram generated for the inner ear of the recipient.

17. The apparatus of claim 12 , further comprising:

an intra-cochlear stimulating assembly configured to be implanted in an inner ear of a recipient, wherein the intra-cochlear stimulating assembly comprises a plurality of stimulating contacts configured to obtain the at least one auditory nerve neurophonic and the at least one cochlear microphonic.

18. One or more non-transitory computer readable storage media encoded with instructions that, when executed by one or more processors, cause the one or more processors to:

obtain at least one measure of outer hair cell function from a tonotopic region of an inner ear of a recipient of a hearing prosthesis;

obtain at least one measure of auditory nerve function from the tonotopic region of the inner ear of the recipient, wherein the at least one measure of outer hair cell function and the least one measure of auditory nerve function are evoked in response to acoustic stimulation signals delivered to the inner ear;

compare a value associated with the at least one measure of auditory nerve function to a value associated with the at least one measure of outer hair cell function;

provide at least one of a visible or audible indication of a result of the comparing of the value associated with the at least one measure of auditory nerve function relative to the value associated with the at least one measure of outer hair cell function;

identify a dead region of the inner ear based on a deviation between the at least one measure of auditory nerve function and the at least one measure of outer hair cell function; and

generating an acoustic prescription for the recipient that excludes fitting frequencies corresponding to the dead region.

19. The non-transitory computer readable storage media of claim 18 , wherein the instructions operable to compare the value associated with the at least one measure of auditory nerve function to the value associated with the at least one measure of outer hair cell function comprise instructions operable to:

determine whether the at least one measure of auditory nerve function differs from an expected measure of auditory nerve function for the tonotopic region the inner ear;

determine whether the at least one measure of outer hair cell function differs from an expected measure of outer hair cell function for the tonotopic region the inner ear; and

analyze any differences between the at least one measure of auditory nerve function and the expected measure of auditory nerve function relative to any differences between the at least one measure of outer hair cell function and the expected measure of outer hair cell function.

20. The non-transitory computer readable storage media of claim 18 , wherein:

the instructions operable to compare the value associated with the at least one measure of auditory nerve function to the value associated with the at least one measure of outer hair cell function comprise instructions operable to analyze the at least one measure of auditory nerve function relative to the at least one measure of outer hair cell function to determine whether the tonotopic region of the inner ear has a physiological abnormality, and

wherein the instructions operable to provide at least one of a visible or audible indication of a result of the analysis of the at least one measure of auditory nerve function relative to the at least one measure of outer hair cell function comprise instructions operable to provide at least one of a visible or audible indication of the physiological abnormality.