The evaluation of cochlear implant users' acoustic change detection ability

This study aimed to investigate the relationship between behavioral and electrophysiological measures in response to acoustical change in adult cochlear implant users. Twenty-eight users participated in this study. Acoustic change detection threshold test and Turkish Matrix Test were performed in individuals as behaviorally. Acoustic change detection threshold test was performed via Staircase Simple Up Down method and the detection threshold of change (Hz) which is done in /ui/ speech material was found in each individual. The Speech Reception Threshold (dB) and Speech Intelligibility performance (%) of individuals were measured via Turkish Matrix Test (in quite condition). Acoustic change complex potentials were recorded as a response to change in /ui/ speech material in electrophysiological measurements. The N1-P2 amplitude (µv) and N1 latency (msec) were evaluated in the onset and change responses. A significant relationship between behavioral and electrophysiological measures in individuals was not found. However, when the distribution of individuals in terms of behavioral responses was investigated, two groups could be determined. A significant difference between groups was found in terms of acoustical change detection thresholds (p<0,05). Moreover, there was a significant difference was found in N1-P2 amplitude and N1 latency measures of change responses when electrophysiological responses of groups were compared (p<0,05). In the group which has better detection thresholds, mean value of N1-P2 amplitude was found higher and mean value of N1 latency was found longer. As a result, this study suggests that when the cochlear implant users are grouped in terms of behavioral responses, a good agreement would be seen between behavioral and electrophysiological measures.