The physical shape of cochlear implant (CI) arrays may impact hearing outcomes. The goal of this study was to compare post-operative speech and melody perception between patients with lateral wall (LW) and perimodiolar (PM) electrode arrays across a range of lengths and manufacturers. Retrospective chart review. Tertiary Care Hospital. 119 adult patients with post-lingual hearing loss who underwent cochlear implantation. A total of seven different electrodes were evaluated including 5 different LW electrodes (CI422 [Cochlear American], 1J [Advanced Bionics], Medium [Med El], Standard [Med El], Flex28 [Med El]) and 2 PM electrodes (Contour [Cochlear American], MidScala [Advanced Bionics]). Speech perception outcomes (n = 119 patients) were measured by Consonant-Nucleus-Consonant (CNC) scores collected 3, 6, 12 and 24 months after implantation. Melody perception outcomes (n = 35 CI patients and n = 6 normal hearing patients) were measured by Melodic Contour Identification (MCI). CNC scores increased over time after implantation across all array designs. PM designs exhibited higher CNC scores compared to LW electrodes, particularly 6-months after implantation. Pre-operative pure tone averages did not correlate with post-operative CNC scores. PM arrays outperformed LW electrodes in terms of MCI scores. The physical shape of cochlear implant electrode arrays may impact hearing performance. Compared to LW designs, PM arrays appear to offer superior speech perception during the first 6 months after implantation, with performance equalizing between groups by 24 months. Compared to LW designs, PM arrays also appear to afford superior melody perception.