can someone tell me what this sound is and how to fix it

 

could be a million things by that description. There are lots of small vacuum lines around the intake box, a few big ones as well. I'd check them all with a bright light. If it was fuel or coolant you'd see or smell it.

 

more info? Gutted airbox. kn intake, random crap intake will all make noise. If you have a stock airbox then I am sure you have a loose vaccum line OR PCV line is corroded out from the oil coming back through it...change PCV valve&hose

 

Cobras in your intake