Noise...

"The noise was quite disruptive at first, but after about four minutes the subjects were doing just as well on their tasks.... Their physiological arousal also declined quickly....."

Just wondering what the "physiological arousal" refers to? Alertness to the noise?

This is from the past paper of an exam about the effects of noise on people working on some tasks. The whole paragraph is a bit long. If the above info is not enough I will post the paragraph.

Thanks.