Clinical Psychoacoustics Laboratory

Cochlear Implant Research

Our current research investigates the auditory analyzing capabilities of electric hearing. This research uses psychophysical measures of electrical hearing to investigate limitations in auditory analysis that may affect the perception of speech and other sounds through a cochlear implant. Work in the current proposal focuses on the spatial resolution needed to resolve spectral acoustic cues. Cochlear implants encode stimulus frequency by electrode position along the cochlear duct, with the assumption that different electrodes excite unique populations of auditory nerve fibers. This assumption may be violated in the case of reduced neural survival; thus, individual differences in spatial resolution may explain much of the variability in speech recognition observed among cochlear implant users. Psychoacoustic experiments proposed in this project aim to characterize individual differences in spatial resolution, to compare different measures of spatial resolution, and to determine which measures of spatial resolution predict speech perception in quiet and in noise. Forward-masked spatial tuning curves (fmSTCs) obtained with a fixed-level probe will provide measures of spatial selectivity across electrodes, and evaluation of the tip locations of fmSTCs for different probe electrodes will provide an estimate of neural distribution patterns, or neurotopicity. Measures of spatial resolution obtained from fmSTCs will be compared to measures of tonotopicity (electrode pitch magnitude estimation and electrode pitch ranking), and other measures of spatial resolution that may be clinically practicable (across-channel gap detection and phase-dependent threshold shift). The general hypothesis is that measures obtained at stimulus levels near threshold will provide evidence of the distribution of surviving auditory nerve fibers and of spatial selectivity, whereas measures performed at suprathreshold amplitudes will reflect the spatial resolution capabilities of large regions of auditory nerve fibers, but will provide less information about nerve-fiber distributions or spatial selectivity. The effects of stimulus level, pulse rate and electrode configuration will be assessed for selected measures of spatial resolution. Measures of spatial resolution will be related to measures of speech recognition in quiet and noise, including measures of spectral and temporal cue perception. Findings should enhance our understanding of spatial phenomena in electrical hearing and lead to improved strategies for mapping speech processors in individual patients.

Our current research is funded by grant R01-DC006699 titled
Auditory Analysis in Electric Hearing (David A. Nelson, Ph.D., Principal Investigator),
awarded by the National Institute of Deafness and Communication Disorders NIDCD.
This research also receives local funding from the Lions 5M International Hearing Foundation.

Our previous research investigated the auditory-processing capabilities of deaf cochlear-implant listeners with usable electric hearing. The research was divided into four areas of investigation. In the first, experiments investigated the intensity limits for effective sensory channel separation between electrodes. In the second, the limitations and perceptual attributes associated with place and periodicity coding were investigated. In the third area of investigation, the dependence of perceived loudness on stimulus intensity was examined and the limits of intensity coding were determined. In the fourth area, measures of auditory-processing capability, obtained in the previous three areas, were related to the ability to process speech sounds and to current speech-processor schemes.

Our previous research was funded as part of Project #1 in the program project grant P01-DC00110 titled
Mechanisms of Auditory and Vestibular Dysfunction(David A. Nelson, Ph.D., Program Director),
awarded by the National Institute of Deafness and Communication Disorders NIDCD.
This research also received local funding from the Lions 5M International Hearing Foundation.


Publications: (click on a link for a pdf reprint of the publication)

NELSON, D.A., DONALDSON, G.S. and KREFT, H.A. (2008). “Forward-masked spatial tuning curves in cochlear implant users,” J. Acoust. Soc. Am., 123, 1522-1543.

DONALDSON, G.S. and KREFT, H.A. (2006). Effects of vowel context on the recognition of initial and medial consonants by cochlear implant users. Ear and Hearing, 27, 658-677.

DONALDSON, G.S., KREFT, H.A. and LITVAK, L. (2005). Place-pitch discrimination of single- versus dual-electrode stimuli by cochlear implant users. J. Acoust. Soc. Am., 118, 623-626.

KREFT, H.A., DONALDSON, G.S. and NELSON, D.A. (2004). Effects of pulse rate and electrode array design on intensity coding in cochlear-implant users. J. Acoust. Soc. Am., 116, 2258-2268.

KREFT, H.A., DONALDSON, G.S. and NELSON, D.A. (2004). Effects of pulse rate on threshold and dynamic range in Clarion cochlear-implant users. J. Acoust. Soc. Am.,115, 1885-1888.

WOJTCZAK, M., DONALDSON, G.S. and VIEMEISTER, N.F. (2003). Intensity discrimination and increment detection in cochlear-implant users. J. Acoust. Soc. Am., 114, 396-407.

DONALDSON, G.S., and ALLEN, S.L. (2003). Effects of presentation level on phoneme and sentence recognition in quiet by cochlear implant listeners. Ear and Hearing, 24, 392-405.

MUNSON, B., DONALDSON, G.S., ALLEN, S., COLLISON, E.A. and NELSON, D.A. (2003). Patterns of phoneme perception errors by listeners with cochlear implants varying in overall speech perception ability. J. Acoust. Soc. Am., 113, 925-935.

NELSON, D.A. and DONALDSON, G.S. (2002). Psychophysical recovery from pulse-train forward masking in electric hearing. J. Acoust. Soc. Am., 112, 2932-2947.

NELSON, D.A., and DONALDSON, G.S. (2001). Psychophysical recovery from single-pulse forward masking in electric hearing. J. Acoust. Soc. Am., 109, 2921-2933.

DONALDSON, G.S., PETERS, M.D., ELLIS, M.R., FRIEDMAN, B.J., LEVINE, S.C. and RIMELL, F.L. (2001). Effects of the Clarion electrode positioning system on auditory thresholds and comfortable loudness levels in pediatric patients with cochlear implants. Arch. Otol. Head Neck Surg., 127, 956-960.

DONALDSON, G.S. and VIEMEISTER, N.F. (2000). Intensity discrimination and detection of amplitude modulation in electric hearing. J. Acoust. Soc. Am., 108, 760-763

DONALDSON, G.S. and NELSON, D.A. (2000). Place-pitch sensitivity and its relation to consonant recognition by cochlear implant listeners using the MPEAK and SPEAK speech processing strategies. J.Acoust. Soc. Am., 107, 1645-1658.

JAVEL, E. and VIEMEISTER, N.F. (2000). Stochastic properties of cat auditory nerve responses to electric and acoustic stimuli and applications to intensity discrimination. J. Acoust. Soc. Am., 107, 908-921.

JAVEL, E., and SHEPHERD, R.K. (2000). Electrical stimulation of the auditory nerve. III. Temporal fine structure and action potential initiation sites. Hear. Res., 140, 45-76.

SHEPHERD, R.K., and JAVEL, E. (1999). Electrical stimulation of the auditory nerve. II. Effect of stimulus waveshape on single fibre response properties. Hear. Res., 130, 171-188.

DONALDSON, G.S., VIEMEISTER, N.F. and NELSON, D.A. (1997). Psychometric functions and temporal integration in electric hearing. J. Acoust. Soc. Am., 101, 3706-3721.

NELSON, D.A., SCHMITZ, J.L., DONALDSON, G.S., VIEMEISTER, N.F. and JAVEL, E. (1996). Intensity discrimination as a function of stimulation level with electrical stimulation. J. Acoust. Soc. Am.,100, 2393-2414.

NELSON, D.A., VAN TASSEL, D.J., SCHRODER, A.C., SOLI, S. and LEVINE, S. (1995). Electrode ranking of "place pitch" and speech recognition in electrical hearing. J. Acoust. Soc. Am., 98, 1987-1999.

VAN TASELL, D.J., GREENFIELD, D.G., LOGEMANN, J.L. and NELSON, D.A. (1992). Temporal cues for consonant recognition: training, talker generalization, and use in evaluation of cochlear implants, J. Acoust. Soc. Am., 92, 1247-1257.

KIMBERLEY, B.P., LEE, A., SCHELLER, L., LEVINE, S., ADAMS, G. and NELSON, D.A.(1989). Cochlear-implant hearing performance at the University of Minnesota, J. of Otolaryngology, 18, 24-27.

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Posters/Presentations:

CRUMP, E.S., NELSON, P.B., NELSON, D.A., KREFT, H.A., CARSON, M. and JAEGER, L. (2007). The relationship between spatial tuning curves and speech recognition in cochlear implant listeners. 2007 Conference on Implantable Auditory Prostheses. Lake Tahoe, CA (July).

NELSON, D.A., DONALDSON, G.S., and KREFT, H.A. (2007). Comparison of psychophysical tuning curves in acoustic and electric hearing. 2007 Conference on Implantable Auditory Prostheses. Lake Tahoe, CA (July).

DONALDSON, G.S. and KREFT, H.A. (2006). Effect of vowel context on consonant recognition by CI users. Amer. Acad. Aud., Minneapolis, MN (April).

DONALDSON, G.S., NELSON, D.A. and KREFT, H.A. (2005). Growth of masking functions for interleaved pulse trains. 2005 Conference on Implantable Auditory Prostheses. Asilomar, CA (August).

NELSON, P.B. and JIN, S-H. (2005). Factors affecting implant listeners’ speech understanding in noise. 2005 Conference on Implantable Auditory Prostheses. Asilomar, CA (August).

DONALDSON, G.S., KREFT, H.A. and LITVAK, L.M. (2005). Place-pitch discrimination of single- versus dual-electrode stimuli by cochlear implant users with the Clairon C-II device. Invited presentation, 10th biennial meeting of the International Collegium of Rehabilitative Audiology, Gainesville, FL. (March).

DONALDSON, G.S., KREFT, H.A., LITVAK, L., MISHRA, L. and OVERSTREET, E. (2004). Steering current through simultaneous electrode stimulation in the Clarion CII: Place-pitch resolution. 8th International Cochlear Implant Conference, Indianapolis, IN. (May).

DONALDSON, G.S., KREFT, H.A. and NELSON, D.A. (2004). Psychophysical estimates of spatial selectivity and neural survival. 8th International Cochlear Implant Conference, Indianapolis, IN (May).

BECKEN, E.T., DONALDSON, G.S., KIMBERLEY, B.P. and NELSON D.A. (2004). The relationship between neural survival and psychophysical measures of electric hearing in Nucleus-22 cochlear implant users. Am. Acad. Otolaryngol. Head Neck. February.

DONALDSON, G.S. and VIEMEISTER, N.F. (2002). TMTFs in cochlear implant users: The role of loudness cues. Abstracts 24th ARO Midwinter Mtg.

KREFT, H.A., DONALDSON, G.S. and NELSON, D.A. (2002). Intensity discrimination in Clarion cochlear implant users: Effects of pulse rate and electrode type. Abstracts 24th ARO Midwinter Mtg.

DONALDSON, G.S. and VIEMEISTER, N.F. (2001). Effects of pulse duration on psychometric functions for detection and temporal integration functions in cochlear-implant listeners. Abstracts 2001 Conference on Implantable Auditory Prostheses (Pacific Grove, CA).

KREFT, H.A., DONALDSON, G.S. and NELSON, D.A. (2001). Effects of electrode positioning system and stimulation rate on threshold, dynamic range and intensity resolution in Clarion cochlear-implant listeners. Abstracts 2001 Conference on Implantable Auditory Prostheses (Pacific Grove, CA).

WOJTCZAK, M., DONALDSON, G.S. and VIEMEISTER, N.F. (2001). Intensity discrimination and increment detection in electric hearing. Abstracts 141st Meeting of the Acoustical Society of America (Chicago, IL).

OPIE, J.M and DONALDSON, G.S. (2000). Effects of speech processor input dynamic range on speech recognition in noise by Clarion CIS users. CI 2000: The 6th International Cochlear Implant Conference. Miami Beach, FL.

DONALDSON, G.S. and VIEMEISTER, N.V. (1999). Intensity discrimination and modulation detection in electrical hearing. Abstracts 22nd ARO Midwinter Research Meeting.

VIEMEISTER, N.F., DONALDSON, G.S. and NELSON, D.A. (1999). Comparison between the basic psychophysics of acoustic and electric hearing. 1999 Conference on Implantable Auditory Prostheses (Asilomar, CA).

OPIE, J.M., MILLS, D., SOLI, S., DONALDSON, G.S., and SMITH, S.L. (1999). New directions in speech perception testing in noise for cochlear implant recipients. American Academy of Audiology Annual Convention.

OPIE, J.M., SOLI, S.D., DONALDSON, G.S., SMITH, S. and MILLS, D. M. (1999). Modified adaptive speech recognition in noise testing with cochlear implant listeners. 1999 Conference on Implantable Auditory Prostheses (Asilomar, CA).

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Updated: March 9, 2009 by Lab Personnel   (University of Minnesota)
URL: http://www.cpl.umn.edu/implants.htm   (Clinical Psychoacoustics Laboratory)