ambient noise level

基本解释

NIGHTINGALES have complex songs to communicate and adjust their calls according to the ambient noise level.
夜莺唱歌曲调富变化，音量会视环境而调整。
blog.sina.com.cn
On the subway system here in Boston, the ambient noise levels are very comparable to the level on an airplane, although it sounds very different.
在波士顿的铁路系统中，其环境噪音水平与飞行中的飞机不相上下，虽然它们听起来不大一样。
Underwater acoustic channel is a time-space-frequency variant channel, having a character for narrow bandwidth, high ambient noise level and strong interference of multipath.
而由此构成的水声信道是一个空间与频率响应随机快速变化的传输信道，存在窄带、高噪及强多途干扰。
51lunwen.net

It would even apparently incorporate a noise meter that could automatically trigger various options when the ambient noise hits a certain level.
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