Influence of Electric-Acoustic Masking on Speech Perception in EAS Users

Cochlear implant (CI) users with ipsilateral residual hearing combine acoustic and electric stimulation in one ear both (EAS). In EAS users, masking can be shown for electric probes under the influence of acoustic maskers and vice versa, for simultaneous stimulation as well as for non-simultaneous stimulation. A chronic study was used to investigate the relation between masking effects and speech reception.

Fifteen MED-EL Flex electrode users with ipsilateral residual hearing participated in an electric-acoustic masking experiment. Psychoacoustic methods were used to measure the changes in thresholds due to the presence of maskers. Additionally, different fitting strategies were tested with the OLSA Oldenburg sentence test to investigate the relation to residual hearing and masking effects. A newly developed fitting strategy that takes into account the individual masking effects was tested and compared to the standard fitting strategie.

Behavioral thresholds of probe tones, either electric or acoustic, were significantly elevated in the presence of acoustic or electric maskers, respectively. Electric-on-acoustic masking showed more pronounced but narrower masking effects. With increasing residual hearing, speech reception thresholds decrease from meaned 0 to -3 dB SNR, while threshold elevation of acoustic probes increases from 2 to 25 dB. Primary analysis does not show a detrimental effect of masking, but do show a decrease in speech perception with an overlapping fitting for good residual hearing.

This work was supported by the DFG project number 396932747 (PI: Waldo Nogueira), the DFG Cluster of Excellence EXC 1077/1 „Hearing4all“ and MED-EL Medical Electronics.

Publication History

Publication Date:
23 April 2019 (online)