Large odontocetes are considered at risk of auditory and behavioral impacts from sonar, and it is necessary to predict the effects of tonal sonar signals that have widely varying durations. Here, the effect of sound duration on hearing threshold and reaction time was investigated in two killer whales (Orcinus orca) using behavioral methods. Hearing tests were conducted using sounds between 50 μs and 2 s in duration for frequencies across the hearing range. Hearing thresholds within each frequency were dependent on sound duration, with threshold increasing with duration out to a plateau, which was used to calculate auditory integration time. Vocal response reaction time data showed decreasing latency with increasing signal level and length. These data were consistent with other marine mammal species and demonstrate that signal detection and behavior are affected by the duration of tonal sounds in killer whales.