请问句中的 there had never 是完成时态还是什么?a new listener in 1967 might well feel that there had never been any sounds like that in the world before.为什么要用might？

请问句中的 there had never 是完成时态还是什么?
a new listener in 1967 might well feel that there had never been any sounds like that in the world before.
为什么要用might？