After a few seconds, when the X-15 was safely away, the pilot started its rocket engine.

VOA: special.2010.07.07

The headphones are amplifying their heartbeat and the slides are moving one after another for a few seconds each slide and they're listening to their heartbeat.

耳机放大他们的心跳,幻灯片一张接一张,每张停留几秒钟,他们听着自己的心跳。

耶鲁公开课 - 心理学导论课程节选