A sound in the ocean is just that a sound in the ocean ... the US Navy I suspect by now has captured every sound that an enemy combat capable ship ( including Russian and Chinese) submarines, has made.
The sonar soundmen on submarines (not surface ships yet) then consults his sound graph reader called a BQQ-13 and based on machinery noise alone can classify any contact.
The real problem is what is the range of said contact to add in to the firing configuration, but with a active ranging torpedo all you have to do is fire it in the general direction based on one contact of course or it would attack anything in the ocean.
Submarines are great, but it really depends on the sonarman and the captain doing his job correctly.
Unless they are already on patrol the Russians will never make it through it's transit zones to go to war.nor will the US Navy's submarines in Washington and Virgina and Georgia. Perhaps Pearl and Guam might get a few out.
Then you have nasty things called mines that can be planted to come up and smack anything they are programed to hear.
The point is these things are made to protect the mother country and we will probably never know which side wins.
Don't be afraid be ready
Go Navy
