The Role of Autosensitivity Control (ASC) in Cochlear Implant Recipients.

Federica Di Berardino,Daniela Soi,Diego Zanetti,Sandro Burdo,Lara Dalla Costa

doi:10.3390/audiolres11010003

Abstract

The purpose of the study was to examine the subjective and objective potential advantage for speech understanding in noise achieved by cochlear implant (CI) recipients when using the autosensitivity control (ASC) input signal processing in combination with the adaptive dynamic range optimization (ADRO). Eighteen subjects (8 females, 10 males, mean age 17.7 ± 6.7) were enrolled in a prospective open blinded comparative study between the ASC + ADRO condition vs. the ADRO alone; 16 were sequential binaural and 2 were monoaural CI recipients. All patients had been wearing their CI for at least 3 years, had no additional disabilities, had an age-appropriate receptive and expressive language. Word recognition performances in noise (at signal-to-noise ratio +5 dB HL) were significantly better in the ADRO-alone condition than in the ADRO + ASC condition. (p = 0.03) These objective outcomes were in agreement with the subjective reports. No significant difference was found in quiet. Our results, apparently in contrast with other reports in the literature, suggest that the decision of adding the slow-acting automatic reduction in microphone sensitivity provided by ASC should be limited to selected CI recipients.

Highlights

Among the input signal pre-processing systems of cochlear implantations (CI), many authors have described the benefits of the autosensitivity control (ASC) [1,2,3,4,5,6]
word recognition score (WRS) in quiet were not statistically different between ASC + adaptive dynamic range optimization (ADRO) compared to ADRO alone
When the speech tracking task was performed with a masking noise, the difference between ADRO + ASC and ADRO alone was significant: 15 out of 18 patients

Summary

Introduction

Among the input signal pre-processing systems of cochlear implantations (CI), many authors have described the benefits of the autosensitivity control (ASC) [1,2,3,4,5,6]. The ASC was firstly introduced in the body-worn mini sound processor in 1989 by Cochlear Limited (Lane Cove, Australia) [7] and was designed to improve speech recognition by keeping the speech level in the comfortable loudness region in the presence of background noise [8]. It is a slow-acting linear compression pre-processing system that acts after the amplification performed by the speech-processor microphone; its purpose is to optimize the speechto-noise ratio, based on the unmodulated noise input (“noise floor”) of the surrounding environment [9]. In order to reduce the effect of impulsive noises, another pre-processing automatic gain control (AGC)

Methods

Results

Discussion

Conclusion