Time running short as search for Titanic sub focuses on undersea sounds

Rescuers searching for a missing submersible near the wreck of the Titanic on Wednesday concentrated their efforts on a remote area of the North Atlantic where undersea noises have been detected, though officials cautioned the sounds may not have originated from the vessel.
With estimates suggesting the air supply on board could run out in a matter of hours, an international coalition of rescue teams was sweeping a vast expanse of the ocean for the Titan, which vanished on Sunday while…