The thresholds for the detection of frequency transition were obtained for the tone bursts in which the frequency was linearly changed from the initial value of 1000 Hz either during almost the whole burst duration or during a portion of it. The onset of transient had various delays from the beginning of the tone burst. The burst durations were 32, 102, 302, and 1000 msec. It was found that the nearly constant thresholds were obtained for a given burst duration as long asW(=T1+13T2)was held constant, whereT1was the duration of the initial segment of steady frequency andT2was the duration of frequency transition. The thresholds were greater when the transition occurred near the burst onset than when it occurred near the cutoff, and in the former case, the thresholds were influenced by a rise time of tone burst. The thresholds were smallest when the frequency transitions occurred in the middle of the tone burst. It is suggested that there are two mechanisms for auditory detection of frequency transition: one is based on the pitch difference and the other on the gliding pitch.