声强起伏，声强在短时间内的迅速无规变化注 sound intensity fluctuation 在短短的大约5年时间内那个人就由贫致富 the man went from rags to riches in a short period of about five years ..
双语例句
1
For a fixed sound source depth, the acoustical fields caused by high send frequency has strong soundintensityfluctuation, and their variation is sharp enough in an adjacent range.