Enhanced methods for determining iso-loudness contours for fitting cochlear implant sound processors
View Patent ↗Methods are taught to simplify the cochlear implant fitting process for various cochlear prostheses and stimulation strategies, including high rate stimulation strategies. For instance, patient self-programming is made possible. In addition, auto-fitting is made possible (particularly useful for very young patients and other patients for whom it is challenging to obtain feedback) using iso-neural response contours which can be linearly transposed to arrive at iso-loudness contours. Furthermore, M iso-loudness contours (or iso-neural contours) can be linearly transposed to determine T iso-loudness contours. In addition, wider pulse widths can be used to generate an iso-loudness contour whose shape can be used (via linear transposition) to program high-rate, narrow pulse width stimulation.
1. A method of fitting a cochlear implant, the cochlear implant having an electrode array with multiple electrode contacts through which a pulsatile stimulation waveform having a pulse rate and a pulse width may be applied to the cochlea of the patient; and wherein the fitting method builds an M iso-loudness contour and determines a T iso-loudness contour, the method comprising:
a) setting a starting sound level to build an iso-loudness contour;
b) setting volume on a first channel until the sound is at a predetermined level;
c) adjusting volume on a second channel until the volume of sound on the second channel is similar to the volume of sound on the first channel; then
d) setting the next channel to result in the same sound volume determined for the previous channel;
e) repeating step (d) for each available channel until the stimulation level for the last channel is adjusted, and the M iso-loudness contour is built; and
f) picking one channel and determining the volume level of that one channel; and
g) generating a T-iso-loudness contour by determining the difference in the volume level measured for the one channel in step f) and the M volume level found previously for that channel and linearly shifting the M iso-loudness contour by the determined difference in volume level.
2. The method of claim 1 wherein the starting sound level is no sound.
3. The method of claim 1 wherein the sound includes a tone or tones.
4. The method of claim 1 wherein the sound includes noise.
5. The method of claim 1 wherein the sound includes speech.
6. The method of claim 1 wherein the predetermined level is a comfortable level.
7. The method of claim 1 wherein the predetermined level is a threshold level.
8. The method of claim 1 wherein at least one channel is a virtual channel.
9. The method of claim 1 wherein at least one channel is skipped.
10. A method of fitting a cochlear implant, the cochlear implant having an electrode array with multiple electrode contacts through which a pulsatile stimulation waveform having a pulse rate and a pulse width may be applied to the cochlea of the patient; and wherein the fitting method sets an iso-loudness contour from an iso-neural response contour, the method comprising:
determining an iso-neural response contour; and
linearly transposing the iso-neural contour to set an iso-loudness contour.
11. The method of claim 10 further comprising using at least one of neural response imaging and evoked auditory brainstem response to determine the iso-neural response contour.
12. The method of claim 10 further comprising
determining an M level for at least one channel;
determining a difference between the iso-neural level and the M level for the at least one channel; and
linearly transposing the iso-neural contour by the amount of the difference to set the iso-loudness contour.
13. The method of claim 10 wherein the iso-loudness contour is an M iso-loudness contour.
14. The method of claim 10 wherein the iso-loudness contour is a T iso-loudness contour.
15. A method of fitting a cochlear implant, the cochlear implant having an electrode array with multiple electrode contacts through which a pulsatile stimulation waveform having a pulse rate and a pulse width may be applied to the cochlea of the patient; and wherein the fitting method uses at least two iso-loudness contours, the method comprising:
determining a first iso-loudness response contour; and
linearly transposing the first iso-loudness contour to set a second iso-loudness contour.
16. The method of claim 15 wherein the first iso-loudness contour is an M iso-loudness contour.
17. The method of claim 16 wherein the second iso-loudness contour is a T iso-loudness contour.
18. The method of claim 15 further comprising:
determining a difference between the first iso-loudness contour level and the second iso-loudness contour using at least one channel; and
linearly transposing the first iso-loudness contour by the amount of the difference to set the second iso-loudness contour.
19. A method of fitting a cochlear implant, the cochlear implant having an electrode array with multiple electrode contacts through which a pulsatile stimulation waveform having a pulse rate and a pulse width may be applied to the cochlea of the patient; and wherein the fitting method determines an iso-loudness contour, the method comprising:
setting pulse width to about 30 μs to about 75 μs;
determining an iso-loudness contour with the set pulse width; and
linearly transposing the iso-loudness contour for use with pulse widths of about 10 μs to about 20 μs.
20. The method of claim 19 further comprising:
determining a difference between the iso-loudness contour level with the set pulse width and a comfortable volume for pulse widths of about 10 μs to about 20 μs; and
linearly transposing the iso-loudness contour by the amount of the difference.