The speech tests used to evaluate language performance in patients with bilateral deafness (BiD) and cochlear implant (CI) are problematic if applied to patients with single-sided deafness (SSD) because normal ear hearing should be excluded. Thus, we investigated the feasibility of using wireless connection to evaluate speech intelligibility of the CI ear in patients with SSD. Subjects and. Patients with BiD and SSD were administered the word recognition scores (WRS) and speech intelligibility tests using an iPadbased wireless connection and conventional methods. To exclude normal side hearing in patients with SSD, masking noise and "plugged and muffed" method were used in the WRS and speech intelligibility tests, respectively. In patients with BiD, the WRS and speech intelligibility tests results using wireless connection and conventional methods were similar. In patients with SSD, the WRS using masking noise in the normal hearing ear was similar to that of using wireless connection. However, 3 of 11 patients with SSD showed under-masked results if using the "plugged and muffed" method. Speech intelligibility testing using wireless connection is a convenient and reliable method for evaluating CI performance in patients with SSD. The "plugged and muffed" method is not recommended for evaluating CI performance in patients with SSD.