Tone recognition ability for post-lingually deafened cochlear implant users using pitch information

OBJECTIVE: The present study was aimed to assess the ability of tone recognition performance for postlingually deafed cochlear implanted adults using no-duration tone test materials.

METHOD: Sixteen cochlear implanted users have used their devices at least six months. Ten monosyllabic syllables were selected, and combined with four lexical tones which were made up of 40 tone tokens. Then, these original words were recorded using one adult male and one adult female native Beijing Mandarin speaker. The speakers were asked to record these 40 monosyllabic words multiple times, and the 80 tokens in which the durations of four tones in each monosyllabic word were within 5 ms precision were chosen as the original tone tokens. The subjects were asked to perform a four alternative forced-choice study and select the tone they had heard.

RESULT: The mean score of lexical tone perception tasks for 16 cochlear implanted users is (70.7 ± 22.0)%, and Tone 4 was the easiest to perceive, while Tone 2 was the hardest for cochlear implanted subjects to perceive. Tone 1 was more often misperceived as Tone 2 relative to other tones. Tone 2 was more often misperceived as Tone 1 and 3. Tone 3 was more often misperceived as Tone 2. The tone perception performance was positively correlated with duration of hearing aid use.

CONCLUSION: Duration cues may impact on the ability of tone recognition performance for cochlear implant subjects, especially for tone 3. Due to the limited ability for cochlear implant subjects on pitch perception, tone l and tone 2, and tone 2 and tone 3 are most often confused with each other without duration cues. The experience of hearing aid use may benefit for postlingual deafness cochlear implant recipients on tone perception performance.