laugh tracks 笑声声带

　　encourage us to chuckle 逗得开怀大笑

　　Laugh tracks in television shows like I Love Lucy have been encouraging us to chuckle since the 1950s. But they originated even before that with old radio shows.自上世纪50年代以来，我们一直被《我爱露西》这类电视节目中的笑声逗得开怀大笑。但在此之前，他们就已经开始制作旧广播节目了。

　　be highly contagious 有高度传染性

　　So they started recording them with a live audience because then people had all the cues that they would get if they were at the theaters, say-of an audience response. And, indeed, laughter can be highly contagious."

　　所以人们开始有现场观众的节目上录音，因为如果在影院，人们就会了解观众的反应，而且笑声的确有高度传染性。

　　spontaneous laughter不由自主的笑声

　　The researchers paired the jokes with both spontaneous, involuntary laughter and with laughter that had been produced on demand.

　　研究人员将这些笑话与自发的、不由自主的笑声和按照需求录制的笑声进行对比。