If a rat in a cage is exposed to a sound, the animal initially orients itself toward and pays attention to the sound, but after a few repetitions, the rat ignores it. However, the animal will respond once again if the sound is paired with an electric shock.

윗 문장에서 두번째 문장에 있는 paired의 의미가 파악이 안되네요 ㅠㅠ

faired가 의미하는게 뭔지좀 가르쳐 주세요 ㅠㅠ