The 效果（效应） 产生 by 创作 and sometimes 增加 during 回放 a gap of 时间 between two copies of one 录制 item When the difference is small the 效果（效应） is close to that of a sweeping 滤波器 Augmenting the gap will lead to panoramic motions and further to 回声 源 - Rodolfo Caesar 1992 The 作曲 of 电子声学 音乐 PhD Thesis University of East Anglia