Logatome Discrimination in Cochlear Implant Users: Subjective Tests Compared to the Mismatch Negativity

Abstract

This paper describes a logatome discrimination test for the assessment of speech perception in cochlear implant users (CI users), based on a multilingual speech database, the Oldenburg Logatome Corpus, which was originally recorded for the comparison of human and automated speech recognition. The logatome discrimination task is based on the presentation of 100 logatome pairs (i.e., nonsense syllables) with balanced representations of alternating “vowel-replacement” and “consonant-replacement” paradigms in order to assess phoneme confusions. Thirteen adult normal hearing listeners and eight adult CI users, including both good and poor performers, were included in the study and completed the test after their speech intelligibility abilities were evaluated with an established sentence test in noise. Furthermore, the discrimination abilities were measured electrophysiologically by recording the mismatch negativity (MMN) as a component of auditory event-related potentials. The results show a clear MMN response only for normal hearing listeners and CI users with good performance, correlating with their logatome discrimination abilities. Higher discrimination scores for vowel-replacement paradigms than for the consonant-replacement paradigms were found. We conclude that the logatome discrimination test is well suited to monitor the speech perception skills of CI users. Due to the large number of available spoken logatome items, the Oldenburg Logatome Corpus appears to provide a useful and powerful basis for further development of speech perception tests for CI users.

Saliency of Vowel Features in Neural Responses of Cochlear Implant Users

“…34 We confirm the finding of reduced MMN amplitude in CI users compared with NHs, as reported by many. 28,46,47 In NHs, both F0 and F1 variation induce large amplitude of MMN. This contrasts with a previous report of larger MMN amplitude evoked with F0 changes than with F1 changes.…”

Development and Evaluation of a Language-Independent Test of Auditory Discrimination for Referrals for Cochlear Implant Candidacy Assessment

“…Others have utilized a hearing test online that presented meaningless syllables called “logatomes” in fluctuating interference noise ( Rahne et al 2010 ). After a logatome is presented, a listener is required to identify the syllable heard by selecting from a range of graphically presented meaningless syllables displayed on a monitor or similar device; or reproduce the sound heard so that it may be registered by speech recognition for scoring.…”

Evaluation of an Adaptive Dynamic Compensation System in Cochlear Implant Listeners

“…Faster-acting AGC systems, by narrowing the DR of a signal, can reduce the temporal variations within a logatome. Less salient differences can impair the intelligibility of more complex words and sentences ( Rahne et al., 2010 ). A logatome test therefore represents a good measure to compare different sound processing schemes that affect features of the signal such as its DR.…”