起衰延消 起（始） 衰（减） 延（续） 消（去）/释放 is a 术语 used to 描述 the 形状 of 声 over 时间 see also 包络
•Sounds that begin very quickly for 例如 a click can be 描述 as having a fast 起（始） 声 that begin more gradually can be 描述 as having a slow 起（始） for 例如 the 声波 of an apporaching car Removing the 起（始） of a 声波 can significantly 影响 what we 听 bell 例如

•The 衰（减） of a 声波 is the 时间 which it takes for the 起（始） portion of the 声波 to reach a steady 延（续）

•The 延（续） of a 声波 is how long it continues to 振动 and 声波 A click has very little 延（续） while a bell often has a long 延（续） The 延（续） portion of a 声波 can be isolated and 循环 to extend 声 or to 创作 new and steady 声

•The 消（去）/释放 of the 声波 is the way in which the 声波 finally ends

Affecting the 包络 of a 声波 can greatly change the characteristic of a 声波 When 声 are reversed their 包络 is also reversed and it is often this that leads to the greatest difference in 声波 品质 声波 例如

When 创作 new 声 on a synthesiser it is often 可能 to 控制 the 形状 of ASDR 包络 and when 作曲 with 录制 声 it is often very useful to 想像 the 起衰延消 包络 形状 合并 声 with 类似 包络 形状 can help to link the 声 together 声波 例如 while contrasting 声 that have very diffrerent 起衰延消 envelopes can 创作 rich 质地（纹理、织体）