Speech polar plots for different directionality settings of SONNET cochlear implant processor

Geert De Ceulaer*, David Pascoal, Peter Nopp, Vincent Péan, Paul J Govaerts

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Objectives: The newest CI processor from MED-EL company, the SONNET, has two new directional microphone settings. Besides the Omnidirectional microphone mode, it has the possibility to switch to Natural or Adaptive directionality. Both new modes favour perception of sound coming from a front-facing direction compared to sounds from sources at alternate azimuths. Natural directionality mimics the pinna effect of the normal external ear. Design: We undertook to verify the effect of these options in vivo by means of clinical audiological tests. Speech reception thresholds were successively measured for a variety of speech presentation azimuths while keeping the noise azimuths constant. Complete ‘Speech Reception Threshold (SRT)-Polar-Plots’ were obtained from these data for the Omnidirectional and Natural directionality modes of the SONNET. In addition, one ‘SRT-point’ was also measured in the ‘Adaptive’ mode for speech coming from 45° azimuth. Study sample: A group of 13 adult CI recipients participated. Only one of these subjects had previous experience with the SONNET processor. Results: Complete ‘SRT-Polar-Plots’ could be measured in Natural and Omnidirectional modes in CI recipients within an acceptable timeframe. The pinna-following directionality for Natural mode could be confirmed. Median SRT in noise for speech coming from the 45° azimuth speaker was −5.6 dB SNR for Omnidirectional, −9.1 dB SNR for Natural and −12.8 dB SNR for Adaptive microphone. Natural and Adaptive significantly improved performance compared to Omnidirectional mode at this optimal azimuth of 45° with a median improvement in SRT of 3.5 and 7.2 dB respectively. Conclusions: A novel audiological method, ‘SRT-Polar-Plot’, was developed and described. Significant directionality benefits for Natural and Adaptive mode were confirmed in vivo using this technique.

Original languageEnglish
Pages (from-to)299-311
Number of pages13
JournalCochlear Implants International
Volume20
Issue number6
DOIs
Publication statusPublished - 2 Nov 2019

Keywords

  • Cochlear implant
  • Directional microphone
  • Noise
  • Polar plot
  • Speech perception

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