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

Area of Science:

• Audiology
• Biomedical Engineering
• Hearing Science

Background:

• The MED-EL SONNET cochlear implant (CI) processor features new directional microphone settings: Natural and Adaptive, alongside the standard Omnidirectional mode.
• These directional modes aim to enhance sound perception from specific directions, with Natural directionality mimicking the natural pinna effect.

Purpose of the Study:

• To clinically verify the effectiveness of the SONNET processor's Natural and Adaptive directional microphone settings in vivo.
• To evaluate the impact of these settings on speech reception thresholds in various noise conditions using a novel audiological method.

Main Methods:

• A group of 13 adult cochlear implant recipients participated in the study.
• Speech Reception Thresholds (SRTs) were measured across different speech presentation azimuths with constant noise azimuths.
• Complete 'Speech Reception Threshold (SRT)-Polar-Plots' were generated for Omnidirectional and Natural modes, with an additional measurement in Adaptive mode.

Main Results:

• The 'SRT-Polar-Plot' method proved effective for measuring directionality in CI recipients.
• Both Natural and Adaptive modes demonstrated significant improvements in SRT compared to Omnidirectional mode.
• At a 45° speech azimuth, median SRTs were -5.6 dB SNR (Omnidirectional), -9.1 dB SNR (Natural), and -12.8 dB SNR (Adaptive), showing median improvements of 3.5 dB and 7.2 dB respectively.

Conclusions:

• The study successfully developed and validated the 'SRT-Polar-Plot' as a novel audiological assessment tool.
• Significant in vivo benefits of the Natural and Adaptive microphone directionality modes were confirmed for the SONNET CI processor.