Answer:
It is a sound of empty, speak and it'll talk back plenty. But all the more you yack, you'll get the same words back.
What has to be broken before it can be used?
A mighty weapon in the war against winged household pests.
I am the outstretched fingers that seize and hold the wind. Wisdom flows from me in other hands. Upon me are sweet dreams, my merest touch brings laughter
It's anything but amusing when this body part gets hit.
If itβs information you seek, come and see me. If itβs pairs of letters you need, I have consecutively three. What am I?