What is "master chief petty officer of the navy"

The Master Chief Petty Officer of the Navy (MCPON, pronounced ) is a unique non-commissioned rate of the United States Navy, which has with it the paygrade of E-9. The holder of this rank and position of office is the most senior enlisted member of the U.S. Navy, equivalent to the Sergeant Major of the Army, Chief Master Sergeant of the Air Force, Sergeant Major of the Marine Corps, Master Chief Petty Officer of the Coast Guard, and Senior Enlisted Advisor to the Chairman of the Joint Chiefs of Staff. He is appointed by the Chief of Naval Operations to serve as a spokesman to address the issues of enlisted personnel to the highest positions in the Navy. As such, he is the senior enlisted advisor to the Chief of Naval Operations as well as the Chief of Naval Personnel. His exact duties vary, depending on the CNO, though he generally devotes much of his time to traveling throughout the Navy observing training and talking to sailors and their families. His personnel code is N00A as the senior enlisted advisor to Chief of Naval Operations and PERS-00D in his special advisory capacity to Chief of Naval Personnel/Deputy Chief of Naval Operations (Manpower, Personnel and Training). In 1988, the MCPON's spouse was made the Ombudsman-at-Large, authorizing her to travel around the fleet with her husband, representing the interests of the spouses of enlisted members. While the MCPON is a non-commissioned officer, this billet is protocol equivalent to a vice admiral.