Objective speech intelligibility measurement for cochlear implant users in complex listening environments

Abstract

Objective intelligibility measurement allows for reliable, low-cost, and repeatable assessment of innovative speech processing technologies, thus dispensing costly and time-consuming subjective tests. To date, existing objective measures have focused on normal hearing model, and limited use has been found for restorative hearing instruments such as cochlear implants (CIs). In this paper, we have evaluated the performance of five existing objective measures, as well as proposed two refinements to one particular measure to better emulate CI hearing, under complex listening conditions involving noise-only, reverberation-only, and noise-plus-reverberation. Performance is assessed against subjectively rated data. Experimental results show that the proposed CI-inspired objective measures outperformed all existing measures; gains by as much as 22% could be achieved in rank correlation.

A model that predicts the binaural advantage to speech intelligibility from the mixed target and interferer signals

“…It was tested across different databases and later extended to predict intelligibility . More recently, the SRMR was implemented as a predictor of speech intelligibility in simulated and actual monaural cochlear-implant listening under conditions involving noise-only, reverberation-only and the combined effect of both (Santos et al, 2012;Santos et al, 2013).…”

Objective Quality and Intelligibility Prediction for Users of Assistive Listening Devices: Advantages and limitations of existing tools

“…In order to tailor the SRMR measure for CI, a few modifications were recently implemented [26], [27]. First, the gammatone filterbank was replaced by the filterbank used in the speech coding strategy of the CI devices used by the listeners in the subjective test.…”

“…Lastly, to model the reduced sensitivity of the hearing impaired listeners, the 4 − 128 Hz range of the eight modulation filterbank center frequencies of the original SRMR metric was reduced to 4 − 30 Hz. The SRMR metric tailored to CI (SRMR-CI) has been tested as a correlate of intelligibility for CI users under clean, noisy, reverberant, noise-plus-reverberation, and speech-enhanced conditions [26], [27]. …”

Effect of the degree of sensorineural hearing impairment on the results of subjective evaluations of a noise-reduction algorithm

“…To wirelessly transfer the testing sounds from a computer to the patient-worn device, an iCom accessory for Phonak receivers was utilized. The initial volume of the testing sounds was set to 70 dB, and then each subject was asked to adjust the volume to his/her comfort level (Kusumoto et al, 2005;Santos et al, 2013;Nam et al, 2013). Before the experiment, insert-gains at overall frequency channels were set to 0 dB for the NH subjects, while those for the SNHI subjects were fitted according to the National Acoustic Laboratories nonlinear version 1 (NAL-NL1) formula (Dillon, 1999).…”