How do you get to ames in metal gear solid 2

Head to the shell one core, and once there (i don't remember if you slip on the guard costume automatically or not. If not, put it on) head downstairs to find the room with the hostages. Now pull out the directional microphone item and use it to listen to the hostages heartbeats. One of the hostages, namely Richard Ames, should have an irregularity in his. More specifically - You should be hearing a "beep"-noise with the heartbeats, which is explained by his pacemaker.