Non-steady-state noise was composed of pedestal and intensity increment of 3 dB or 6 dB. The increment occupied one-seventh of whole stimulus duration (350 msec or 700 msec) and its position was systematically shifted. The loudness of non-steady-state noise was obtained by loudness matching, paired comparison and using auditory evoked potential. From these experiments the systematical effect of the position of the increment was noticed. When the increment was situated at the beginning or at the end of the pedestal, the loudness was overestimated. On the other hand, when the increment was situated in the middle of the pedestal, underestimation occurred. An attempt was made to explain this phenomenon by the synchronization of neuron discharge, the auditory adaptation and the temporal inhibition.