mario a. svirsky dept. of otolaryngology new york university school of medicine

New directions in programming: Choosing

frequency allocation tables for postlingually deaf CI users

Mario A. SvirskyDept. of Otolaryngology

New York University School of Medicine

Do postlingually deaf patients adapt completely to the standard

frequency allocation tables?

Hypotheses

1) Human listeners can adapt to frequency-shifted auditory input, even when there’s spectral degradation

2) Some listeners may not adapt completely

3) Individual differences in the ability to adapt completely may have clinical implications and may be addressed by appropriate signal processing.

Four methods to measure adaptation to frequency tables

1) Pitch matching

2) Mathematical modeling of vowel identification

3) Perceptual vowel space

4) Self selection of “most intelligible” frequency table

Method 1: Electroacoustic pitch matching

Most apical electrode (#22), Nucleus device.

Range=188-313 Hz Center=250 Hz

Postlingually deaf adults with different amounts of post-implant experience.

Data from three different laboratories.

Electroacoustic pitch matching- all electrodes

• Six repetitions per electrode• Alternating stimulation to each ear• Acoustic frequency adjusted by the

listener• Randomized starting frequency• Acoustic stimuli presented at

comfortably loud level (when possible)

Chin-Tuan Tan

Ben Guo (did not submit picture)

Bilateral pitch ranking with very different insertion depths- Case 1

• Two Advanced Bionics devices: normal insertion in left ear, only five active electrodes active in right ear (significant bone drillout).

• Right ear had Ineraid device that was explanted; significant bone growth at the time of reimplantation.

• Each electrode in the partial insertion ear was pitch ranked 2 to 5 times to each electrode in the full insertion ear.

• Non-simultaneous presentation• Electrode in the full insertion ear was randomized.• Similar (standard) frequency tables in both ears. • 3 years right; 9 years left.

Right CI: Shallow

Left CI: Full Length

479 Hz

479 Hz

1440 Hz

1440 Hz

1.7 mm

4 mm

Matthew Fitzgerald

2.2 mm

Bilateral pitch ranking with very different insertion depths- Case 2

• Patient with residual hearing received Hybrid-S 10 mm electrode in the left ear.

• Two years after the Hybrid implantation she lost residual hearing in both ears and was then implanted with a standard electrode (24 mm) in the right ear.

• After loss of residual hearing and standard electrode implantation, both processors were programmed with the standard frequency table: 188-7938 Hz.

• At the time of the Reiss et al. study (Ear and Hearing, 2011) she had 2-3 years of experience with these frequency tables.

• She was also tested in our laboratory when she had six years of experience with the standard frequency tables in both ears.

3760 Hz 325 Hz

3 mm

3760 Hz325 Hz

7.8 mm

3.9 mm

Reiss et al. Ear & Hearing 2011

CONCLUSIONS-METHOD 1Pitch matching

• Pitch matching did not always line up with frequency allocation table– Electroacoustic pitch matching of

most apical electrode, or all electrodes.

– Pitch matching across CI ears with different insertion depths.

• There is significant adaptation, but it is not always complete, despite years of experience.


1) Pitch matching




Method 2: Mathematical modeling of vowel identification

Mathematical models of vowel confusion data allow us to measure the mismatch between:

Places of maximal stimulation along the cochlea for a given vowel

Places along the cochlea where the patient expects to be stimulated

Qualitative description of Sagi et al (2010)

Fu et al. experiment• Three postlingually

deaf adults users of SPEAK strategy.

• 4-6 years of experience.

• Three months of experience with new frequency table

Table 1 Table 7 Table 9CF0 75 120 150CF1 175 280 350CF2 275 440 550CF3 375 600 750CF4 475 760 950CF5 575 920 1150CF6 675 1080 1350CF7 775 1240 1550CF8 884 1414 1768CF9 1015 1624 2031CF10 1166 1866 2333CF11 1340 2144 2680CF12 1539 2463 3079CF13 1785 2856 3571CF14 2092 3347 4184CF15 2451 3922 4903CF16 2872 4595 5744CF17 3365 5384 6730CF18 3942 6308 7885CF19 4619 7390 9238CF20 5411 8658 10823

Fu et al. results

Elec.

Freq. 2

1 1502 2603 3964 5875 8336 11337 14888 18979 2361

10 288011 345312 408113 476414 5500

Elec Freq. 1

1 3002 5073 7024 9755 13266 17567 22638 28489 3512

10 425411 507312 597113 694714 80001 2 43 5

11

10

9

8

7

6

5

F2

F1

Sagi E, Fu QJ, Galvin JJ 3rd, Svirsky MA. JARO 2010

CONCLUSIONS-METHOD 2 Mathematical modeling

• CI users show adaptation after they receive a modified frequency allocation table.

• This adaptation may not be complete even after they reach asymptotic speech perception scores.

• Correct pitch matching is necessary but not sufficient to achieve complete adaptation.


1) Pitch matching




Method 3: Perceptual vowel space

A case of complete adaptation and a case of incomplete adaptation to standard frequency tables.

Perceptual vowel space data from one of the asymmetric insertion patients

Patient E1 - 1 Day Post-CI Activation

F1 (Hz)200 300 400 510 630 770 920

F2

(Hz)

630

920

1270

1720

2320

3150

/i/

/A/

/A/

/u//u/

/i/

Patient E1 - 1 Month Post-CI Activation

F1 (Hz)200 300 400 510 630 770 920

F2

(Hz)

630

920

1270

1720

2320

3150

/i/

/A//u/

/A//u/

/i/

Patient E1 - 3 Months Post-CI Activation

F1 (Hz)200 300 400 510 630 770 920

F2

(Hz)

630

920

1270

1720

2320

3150

/i/

/A//u/


F1 (Hz)200 300 400 510 630 770 920

F2

(Hz)

630

920

1270

1720

2320

3150

/i/

/A//u/

Patient E2 - Day of CI Activation

F1 (Hz)200 300 400 510 630 770 920

F2

(Hz)

630

920

1270

1720

2320

3150

/i/

/A/

/A/

/u/ /u/

/i/

Patient E2 - 1 Day Post-CI Activation

F1 (Hz)200 300 400 510 630 770 920

F2

(H

z)

630

920

1270

1720

2320

3150

/i/

/A//A/

/u/

/u/

/i/

Patient E2 - 1 Month Post-CI Activation

F1 (Hz)200 300 400 510 630 770 920

F2

(H

z)

630

920

1270

1720

2320

3150/i/

/A//A//u/

/u/

/i/


F1 (Hz)200 300 400 510 630 770 920

F2

(H

z)

630

920

1270

1720

2320

3150

/i/

/A//A/

/u//u/

/i/


F1 (Hz)200 300 400 510 630 770 920

F2

(H

z)

630

920

1270

1720

2320

3150

/i/

/A//A/

/u/

/u/

/i/

CONCLUSIONS-METHOD 3Perceptual vowel space

• Some listeners adapt completely to the standard frequency tables; others don’t.

• A similar statement can be made about different ears for the same listener.


1) Pitch matching




Current Clinical Practice

• Is this optimal? For postlingually deaf patients, probably not.

We give every cochlear implant patient the same frequency-to-electrode map.

Current Surgical Practice

Cochleas come in different sizes

• Hardy (1938)- cochlear size can vary by as much as 40%.

• Stakhovskaya et al. (2007): SGN frequency map.– 24 mm from the base

• 76 Hz in a 28 mm cochlea• 1,020 Hz in a 42 mm cochlea

– 10 mm from the base• 3,450 Hz• 6,100 Hz

COCHLEAS COME IN DIFFERENT SIZES

• Average basilar membrane length is about 35 mm, but it can range from 28 mm to 42 mm.

Estimated CF of SG cells in a cochlea of length=

Distance from base

L=28 mm L=42 mm

24 mm 76 Hz 1020 Hz

10 mm 3450 Hz 6100 Hz

Evidence suggesting one size does not fit all (frequency tables)

• Skinner et al. (2002)- correlation between insertion depth and speech perception.

• Kos et al. (2007), Gani et al. (2007), Shapiro, Roland, Waltzman (2007)- overinsertion, electrode deactivation, too much bass.

Basic idea: power to the patient (or to the audiologist)

• Selection of frequency-to-electrode maps may be done in real time while the patient “turns a knob” to maximize the intelligibility of running speech.

• This real-time tool may allow:– Faster comparison of different

maps– Better comparison

NEW PARADIGM

• We have developed PC-based fitting methods that allow very quick (or even real-time) adjustment of frequency maps.

• This system can be used with cochlear implant users, or with simulations for normal hearing listeners.

Change blindness demo

Method 4: Self selection of “most intelligible” frequency table

Listeners are asked to select the frequency table that makes speech sound “most intelligible”.

Assumption: when a listener has adapted completely, he selects his everyday frequency table.

Two methods: RTStream for Advanced Bionics patients and Gridstream for Nucleus patients.

REAL TIME SPEECH PROCESSING SYSTEM

Adam Kaiser, MD

Mehmet Aras

Mohamed El-Sharkawy, PhD

Ben Stelle

Shivank Sinha

Tasnim Morbiwala

Ravi Rayala

Megha Daga

Chin-Tuan Tan, PhD

Mario Svirsky, PhD

Technical assistance and equipment from Advanced Bionics (Abhijit Kulkarni) and Cochlear Americas (Chris van den Honert).

RTStream- real time selection of frequency maps

Total frequency range audible by humans

Active filter bank

• Frequency table parameters change depending on which square is selected.

Self-selection of most intelligible frequency table-2

(.wav) (.wav)

(.wav)

(.wav) (.wav)

Subject #1• 74yo M with hearing loss of unknown etiology,

having used a CI for 14 months prior to testing• Comfortably auditioned maps• Selected one equivalent to the standard map he

had been using for years

Subject #2• 74yo F with hearing loss of unknown etiology,

using a CI for 23 months prior• Also quickly explored the 2D space• Selected a map similar, but different from her

standard map

Subjects #3, 4, 5

FREQUENCY TABLE SELECTION“The player lost a shoe”

Fre

qu

ency

(H

z)

0

2000

4000

6000

8000

10000

188-7938“Sounds very high pitched”

63-3372“shoe sounds like sue and the ‘p’is not

there”

313-5188“The ‘sh’ is pretty good here but not

the best”

188-18,000“That’s a REAL sh!”

188-9804“This may be the clearest, may be the first choice”

Svirsky et al., 2011

NULL HYPOTHESIS: complete adaptation

Self-selected frequency tables for users of the Nucleus device

Self-selected frequency tables for users of the Advanced Bionics device

ACUTE CHANGE IN SPEECH PERCEPTION SCORES

CONCLUSIONS-METHOD 4 Self selection of “most intelligible”

frequency table• CI users can comfortably self select their

preferred frequency to electrode table. • For about half of them, this table is different

from the standard frequency table, again suggesting incomplete adaptation in these listeners.

• Even in an acute setting, self selected maps may allow better speech perception for some CI users (2 or 4 out of 13).

• Adaptation to the standard frequency tables may be more difficult in cases of insertions that are either too deep or too shallow.

A few case studies of adaptation (or lack thereof) to frequency

allocation tables

1) Reimplantation of Hybrid-S users

2) Asymmetric electrode insertion across ears

3) Excessively deep insertion

1) SPEECH PERCEPTION IN HYBRID PATIENTS REIMPLANTED WITH A STANDARD

ELECTRODE

2) SPEECH PERCEPTION IN PATIENTS WITH STRONGLY ASSYMETRIC ELECTRODE

INSERTION

ACUTE CHANGE IN SPEECH PERCEPTION SCORES

Electrode 1 initial surgery

Electrode 1regular placement

High frequencies

3) EXCESSIVELY DEEP INSERTION?

Electrode 1regular placement

High frequencies

WilliamShapiro

J. Thomas Roland, Jr.

3) EXCESSIVELY DEEP INSERTION?

Overall Conclusions

• Taken together, data obtained with four different methods suggest that postlingually deaf CI users have a remarkable ability to adapt to a given frequency allocation table.

• However, adaptation may be not always be complete, depending on the interplay between frequency range, insertion depth and cochlear size.

Overall conclusions

• Self selection of frequency tables (and possibly other parameters) is clinically feasible and may be beneficial for some patients.

SOME QUESTIONS

• Who adapts completely and who doesn’t?

• Why do some patients fail to achieve complete adaptation?

• Is there something we can do about it?

• Are placed in the cochlear nucleus

• Are used for patients with a compromised auditory nerve (e.g., NF2)

Auditory Brainstem Implants

Kanowitz et al., 2004

ABI surface electrode

ABI do help speechreading

Schwarz et al., 2008

In non-NF2 patients, ABI provides open-set speech understanding

Colletti and Shannon, 2005

QUESTIONS ABOUT ABIs

• Why do ABI users with NF2 do so much worse that cochlear implant users?

• Why do non-tumor ABI users do so much better than NF2 ABI users?

• Why do children with ABIs do so poorly (not shown)?

FINAL COMMENTS

• Clinical interest : successful replacement of a human sense.

• Scientific interest: platform to answer basic questions about human communication.

• Translational and multidisciplinary research.

• Many unanswered questions.

AcknowledgmentsThis work has been supported by NIDCD (PIs: Chin-Tuan Tan, Matthew Fitzgerald, Arlene Neuman, Mario Svirsky), NIDRR (PI: Elad Sagi) and the AAO-HNS (PI: D. Jethanamest).

Cochlear Americas and Advanced Bionics have loaned equipment, software, and provided technical advice to this project.

We also acknowledge the invaluable assistance of NYU’s Cochlear Implant Center, its Co-Directors J. Thomas Roland, MD and Susan B. Waltzman, PhD, its chief audiologist, William Shapiro, AuD, and the staff.

AcknowledgmentsThis work has been supported by NIDCD (PIs: Chin-Tuan Tan, Matthew Fitzgerald, Arlene Neuman, Mario Svirsky), NIDRR (PI: Elad Sagi) and the AAO-HNS (PI: D. Jethanamest).

Cochlear Americas and Advanced Bionics have loaned equipment, software, and provided technical advice to this project.

We also acknowledge the invaluable assistance of NYU’s Cochlear Implant Center, its Co-Directors J. Thomas Roland, MD and Susan B. Waltzman, PhD, its chief audiologist, William Shapiro, AuD, and the staff.

Arlene Susan

Neuman Waltzman

AcknowledgmentsThe tools for selection of frequency allocation tables described here are patented. The author has not received any royalties from this IP and has pledged to his university that any future royalties will be donated to charity, to avoid conflicts of interest.

The end

From Reiss et al. Ear & Hearing 2011

mario a. svirsky dept. of otolaryngology new york university school of medicine

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