An experiment is reported on the effects of different signal‐onset conditions, as a function of signal frequency, on the minimum audible angle obtained with human listeners in a free‐field localization situation. Transient binaural differences associated with signal onset were computed on the basis of: (1) the binaural distance difference; (2) the headshadow effect; and (3) the rise time of the signal. The results of the experiment indicate that signal onset may be treated as a short‐duration binaural intensity‐difference cue. The implications for a theoretical model of localization are discussed.