Actually to be correct they are not crickets but cicadas that are trying to keep us awake at night just outside the bedroom window.
Many insect make sounds by rubbing their wings or legs together. The cicadas though use an entirely different method to produce their incredibly loud songs. They have a pair of special sound producing organs called "tymbals," located at the base of the abdomen. Inside each tymbal are stiff but flexible ribs supporting a stout membrane. Muscles attached to the ribs pull the tymbal inward, causing it to pop. The tymbal pops again when the tension is released. Rapid contractions and relaxations of the tymbal muscles create the loud, buzzing songs of the cicadas, which are amplified further by a hollow area in the abdomen.
When we first heard them, we thought it was an short somewhere in the builders cables that supplied our electricity.We now know better. It is almost unbelievable that one small insect can make so much noise.