Also the Marines at Camp Pendleton do artillery practice that can be heard up to 50 miles away.
http://www.marines.mil/unit/basecamppendleton/Pages/Information/noiseAdvisory.aspx
We often hear artillery and tanks firing at Ft. Hood which is 60 - 70 miles in a straight line and over 100 by highway.
Simply military practice that sonically extends according to atmospheric conditions. Always has been the case. The Navy, even when I was in, practiced next to the San Clemente island (can't remember the target island name) all the time for their 3 inch guns. Glad they're still practicing. Guns need practice.
Computer controlled missle guidance systems are tested off Pt. Mugu and Port Hueneme installations. Often times, the conspiratists see their contrails as some ET space thing. Dipshits all.
Those two installations have tested missles as far back as me being a teenager. I remember see their trails up into the sky as a 16 year old. It was a cool sight as they left Vandenberg and left a "hot trail" up into the sunset.
The military does what it needs to do to test new systems and have certain installations and target points. This is old news.