There's specialzed hydrophones to locate the pingers.
http://www.phnx-international.com/sp..._SpecSheet.pdf
If they're not already in the area - with all the assets already available - I sure they're on their way. As for the talk about a singaporean submarine joining the search, I think some media misreported the Submarine Rescue Vessel, which is a surface vessel equipped for underwater search and rescue, as a "submarine". It will be far more useful than a submarine.
Edit: Cody Blade - exactly
