2004 crazy noise

I think it has to do with the brake boost, but about every 15 seconds my son’s vehicle gives a chugging noise from the drivers side under the hood. There is no issues with the brakes, currently, but it is very annoying since I’ve had to drive it for the past few days…. Any guesses…or answers…

 

Hard to comment without actually hearing the sound.

 

My brakes seem to make a periodic buzzing noise, like some kind of actuator is turning on and I can feel a change in the brake pedal feel. Only happens when stopped at a light or something and I’m just sitting there pressing the brake. She stops fine and no other issues. Is this sort of what your issue is?