Frequency selectivity improvements in individual cochlear implant users with a biologically-inspired preprocessing algorithm

  • Florian Langner Medizinische Physik and Cluster of Excellence “Hearing4all”, Carl von Ossietzky University, Oldenburg, Germany
  • Tim Jürgens Medizinische Physik and Cluster of Excellence “Hearing4all”, Carl von Ossietzky University, Oldenburg, Germany

Abstract

The ability to distinguish between two sounds of different frequency is known as frequency selectivity, which can be quantified using psychoacoustic tuning curves (PTCs). Normal-hearing (NH) listeners show level- and frequency-dependent sharp PTCs, whereas frequency selectivity is strongly reduced in cochlear implant (CI) users. This study aims at (i) assessing the individual shapes of PTCs measured psycho-acoustically in CI users, (ii) comparing these shapes to those of simulated CI listeners, and (iii) improving the sharpness of PTCs using a biologically-inspired preprocessing algorithm. A 3-alternative-forced-choice forward masking technique was used to assess PTCs in eight CI users (with their own speech processor) and 11 NH listeners (with and without listening to a vocoder to simulate electric hearing). CI users showed large inter-individual variability in sharpness, whereas simulated CI listeners had shallow, but homogeneous PTCs. Furthermore, a biologically-inspired dynamic compression algorithm was used to process the stimuli before entering the CI users’ speech processor or the vocoder simulation. This algorithm was able to partially restore frequency selectivity in both groups, meaning significantly sharper PTCs than unprocessed.

References

Bräcker, T., Hohmann, V., Kollmeier, B., and Schulte, M. (2009). “Simulation und Vergleich von Sprachkodierungsstrategien in Cochlea-Implantaten,” Zeitschrift der Audiologie/Audiological Acoustics, 48, 158-169.

Jürgens, T., Clark, N.R., Lecluyse, W., and Meddis, R. (2014). “The function of the basilar membrane and the MOC reflex mimicked in a hearing aid algorithm,” J. Acoust. Soc. Am., 135, 2385.

Lecluyse, W., Tan, C.M., McFerran, D., and Meddis, R. (2013). “Acquisition of auditory profiles for good and impaired hearing,” Int. J. Audiol., 52, 596–605.

Meddis, R., Clark, N.R., Lecluyse, W., and Jürgens, T. (2013). “BioAid – ein biologisch inspiriertes Hörgerät,” Zeitschrift der Audiologie/Audiological Acoustics, 52, 148-152.

Moore, B.C.J. (1978). “Psychophysical tuning curves measured in simultaneous and forward masking,” J. Acoust. Soc. Am., 63, 524-532.

Nelson, D., Kreft, H.A., Anderson, E.S., and Donaldson, G.S. (2011). “Spatial tuning curves from apical, middle, and basal electrodes in cochlear implant users,” J. Acoust. Soc. Am., 129, 3916-3933.

Oxenham, A.J. and Plack, C. (1998). “Suppression and the upward spread of masking,” J. Acoust. Soc. Am., 104, 3500-3501.

Patterson, R.D., Nimmo-Smith, I., Weber, D.L., and Milroy, R. (1982). “The deterioration of hearing with age: Frequency selectivity, the critical ratio, the audiogram, and speech threshold,” J. Acoust. Soc. Am., 72, 1788-1803.
Published
2015-12-15
How to Cite
LANGNER, Florian; JÜRGENS, Tim. Frequency selectivity improvements in individual cochlear implant users with a biologically-inspired preprocessing algorithm. Proceedings of the International Symposium on Auditory and Audiological Research, [S.l.], v. 5, p. 317-324, dec. 2015. Available at: <https://proceedings.isaar.eu/index.php/isaarproc/article/view/2015-37>. Date accessed: 22 oct. 2017.
Section
2015/5. Compensation strategies for rehabilitation with cochlear implants