Around Dabob bay, hearing low rumble that reminds of thunder in the distance or even like a train yard coming from the sky. Cannot locate the direction and cannot pinpoint where it is from. It is not consistent. It is not a regular beat type sound. It is inconsistent. Got some video of the sound as it was being picked up by the baby monitor. The Baby monitor is next to us in a separate room and does not pick up noises we are making in the room next door. Not the TV or us talking.