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Objectives. Mandarin tone is characterized by its pitch contours or fundamental frequencies. Contemporary cochlear implant (CI) does not deliver sufficient pitch information through its electrical stimulations to the users. Many studies have examined lexical tone recognition in CI users in quiet testing conditions. Results showed variable performance with an average tone recognition of 70 to 80% correct. The purpose of the present study was to investigate Mandarin tone recognition in background noise in prelingually deafened children with CIs. Materials and Methods. A total of 90 prelingually deafened children with CIs and 54 normal-hearing (NH) children as controls were recruited to participate in the study. Mandarin tone recognition was tested using a two-alternative forced-choice paradigm in various signal-to-noise ratio (SNR) conditions (i.e., -6, 0, +6, +12 dB and quiet). Two types of masking noise were used (i.e., speech-spectrum shaped noise and two-talker babbles). Linear correlation analysis was performed to examine possible relationships between the tone-recognition performance of the CI children and the demographic factors. Results and Conclusions. Children with CIs showed overall poorer tone-recognition performance that were particularly susceptible to noise as compared to their NH peers. Most CI children could not be tested at -6-dB SNR. Interestingly enough, the two types of noise produced similar tone-recognition performance in CI users thus showed little masking release with two-talker babbles. Tone confusions between Mandarin tone 2 and tone 3 were most prominent in both CI and NH children. Age at implantation was significantly correlated with tone-recognition performance of the CI children in noise. Therefore, there is a marked deficit in tone recognition in prelingually deafened children with CIs, especially in noise listening conditions that were typical of their everyday life conditions. Early implantation could be beneficial to tone development in pediatric CI users. [ABSTRACT FROM AUTHOR]