It is difficult to predict the speech perception outcomes of cochlear implantation. Previous studies showed that total response electrocochleography (ECochG-TR) may explain the variance in CI performance better than biographic, audiometric, and surgical factors combined. The authors’ objectives were to understand the relationship between ECochG responses at the promontory, extracochlear and intracochlear sites, and to examine the relationship between ECochG-TR and speech-recognition outcomes. The authors measured ECochGs intraoperatively and speech perception preoperatively and three months postoperatively in 96 cochlear implant patients. ECochGs were measured from the promontory, from the round window and also taken intracochlear. It was not possible to do all the three measurements in each subject. Authors found that the EChochG response increased from promontory to round window by 1.6, to just inside scala tympani by 2.6 and after full insertion by 13.1-fold. There was a strong linear correlation between these measurements. Interestingly, duration of hearing loss and duration of severe-to-profound hearing loss did not correlate with CI performance in this study. Promontory ECochG-TR correlated with speech perception outcomes at three months. There was some variability in locating the electrode on the promontory, and other factors that might be responsible for variability in speech performance such as full insertion of the CI electrode were not accounted for. Authors concluded that promontory ECochG recordings could explain a substantial portion of the variability in CI performance and the findings support the translation of transtympanic ECochG into the clinic to help predict postoperative CI performance. Despite the limitations of this study, clinic-based transtympanic promontory ECochG-TR measurements might provide an answer to the selected CI candidates in whom speech perception outcomes, and hence their candidacy, are questionable.