title: Argentine navy says unusual noise heard on day sub disappeared
text: BUENOS AIRES (Reuters) - An unusual noise was detected last week on the day an Argentine submarine went missing, near its last reported position, navy spokesman Enrique Balbi told reporters on Wednesday. Pressed by reporters on the nature of the detected sound, Balbi declined to say whether it indicated an explosion or other emergency aboard the ARA San Juan, which was last heard from on Nov. 15.  