What is my ceiling made of?

[url]https://goo.gl/photos/HLv5WgcCui9kmKuPA[/url] Built in 1970s I think. :Why:

Hello, We have an ongoing issue in one of the bedrooms in our house. It is a new construction house, 2 years of age, which we purchase directly from the builder. The issue is that whenever there are strong winds, the 2 exterior walls in one of the bedroom make “clunk-like” noises, as if wood is hitting wood or sheetrock, perhaps even metal. This issue was more-or-less isolated to one location for the first year of us living in this house. Unfortunately, right now it seems to have spread to at least 3-4 other locations, on both walls of the bedroom which face the exterior of the house. The issue is keeping getting worse than what it was like a year ago. Something is obviously getting looser inside these 2 walls as time goes by. The issue can be replicated at will (by tapping the wall) in at least one location. My builder has previously addressed it during the first year warranty. They broke one wall (from both sides – sheetrock and bricks) but found nothing unusual. However, their efforts were unfortunately insufficient, as it became apparent a few months after they tried to repair this issue, since new sources of the noise became abundant. I did some of my own research, trying to find out the source of the noise. I reached out to outside builders and inspectors, and along the way I have crossed out such possible reasons as plumbing issues, gas pipeline issues, or baffles issues. One inspector has suggested that it could be interior or exterior structural bracing creaking. Thus he has recommended that the builder's engineer of record get involved and come out and review our house structurally. However, before doing that, I wanted to attempt a possibly easier fix. Right now it seems that wind that gets into the walls through the soffits is causing movement of the sheetrock, which in turn touches some of the studs, thus creating this noise. I therefore think this should be an easy fix, with a stud finder and some nails to hammer the sheetrock and the studs together, so that no more movement can be achieved. Then, all that would remain to be done is a spot treatment of the texture, and some paint. What do you think? Should my fix work? Or do you suspect the issue is more complex than that? And should I contact the builder's engineer of record? Finally, do you think that pumping some insulation foam into these 2 affected walls may help in sealing any air gaps that (perhaps) allow for the movements of pieces inside the wall? Thank you!