The influence of stimulation levels on auditory thresholds and speech recognition in adult cochlear implant users

Abstract

Objective: This study aims to evaluate the influence of minimum and maximum stimulation levels on auditory thresholds and speech recognition abilities in adult cochlear implant users.

Method: Fifteen adults implanted with a Cochlear® device with over 12 months listening experience. Participants underwent routine programming for optimization of minimum (T) and maximum comfort (C) stimulation levels, which was saved in Program 1 (MO). Three further maps were constructed artificially adjusting the measured levels: Program 2 – MO with 10 fewer electrical current units at C level (MC-); Program 3 – MO with 10 fewer electric current units at T level (MT−); and Program 4 – MO with 10 more electric current units at T level (MT+). Sound field thresholds, recorded sentence recognition and monosyllable tests were presented in quiet and in noise.

Results: There were significantly better thresholds at 1, 3, 4, and 6 kHz frequencies in MT+ and worse in MC−. A statistically significant difference was observed for sentences in quiet and monosyllables in quiet and noise with changing C levels, with worsening of the results for MC− program.

Conclusion: The results suggest that T levels above the behavioural threshold provided an improvement in sound field thresholds but did not influence performance on speech recognition tests in quiet and in noise. In contrast, C levels below the behavioural comfort level worsened sound field thresholds and led to poorer performance in tests of sentence recognition in quiet and monosyllable recognition in quiet and in noise.

Keywords:

• Cochlear Implant
• Speech Perception
• Auditory Perception
• Auditory Threshold
• Loudness Perception
• Psychoacoustics

Acknowledgements

The authors would like to thank the Department of Otorhinolaryngology and the Otorhinolaryngology Foundation (FORL) for their support to the Fellowship program on Cochlear Implants.

Disclaimer statements

Contributors None.

Funding National Council for Scientific and Technological Development - CNPq.

Conflict of interest None.

Ethics approval Institutional Research Ethics Committee (741,763).

Notes on contributors

Maria Valéria Schmidt Goffi-Gomez, PhD, is the supervising senior audiologist at the Cochlear Implant Group of the Otorhinolaryngology Department of the School of Medicine at University of São Paulo, Brazil.

Kelly Vasconcelos Chaves Martins, PhD, former fellow at the Cochlear Implant Group of the Otorhinolaryngology Department of the School of Medicine at University of São Paulo, Brazil.