Two experiments are reported in which subjects respond to a click placed on a speech sequence, and their responses are analyzed by taking response bias into consideration. In the first experiment, it is shown that clicks objectively placed around the designed boundary of sentences which is added an acoustic feature, are subjectively monitored in or toward that boundary, as well as the major syntactic boundary. In the second experiment, it is shown that such clock displacement occurs, even when the speech materials are meaningless Letter sequences. It is concluded that speech sequences are perceptually segmented by using both acoustic and syntactic cues. It is suggested that sentence perception should involve different processes from those of sentence reproduction in the click localization task.