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 声音 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） 声音 that begin more gradually can be 描述 as having a slow 起（始） for 例如 the 声音 of an apporaching car Removing the 起（始） of a 声音 can significantly 影响 what we 听 bell 例如

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

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

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

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

When 创作 new 声音 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 声音 it is often very useful to 想像 the 起衰延消 包络 形状 合并 声音 with 类似 包络 形状 can help to link the 声音 together 声音 例如 while contrasting 声音 that have very diffrerent 起衰延消 envelopes can 创作 rich 质地（纹理、织体）