The sound of sirens was an omnipresent background noise in New York.

在纽约，警报声是无处不在的背景噪音。

Each recording had a series of rhyming words that the volunteers had to identify for different levels of background noise.

每段录音都有一系列押韵的单词，志愿者们必须在不同程度的背景噪声下识别这些单词。

People alter their voices in relationship to background noise.

人们根据环境噪音的大小调节自己的声音。

He dubbed out the background noise.

他抹去了背景噪音。

Reduce background noise.

减小背景噪音。