Some humans perceive the beat better when responding to only visual cues.
See if the student can play the bass drum accurately with a conductor and no sound in the room. Vary the tempo to ensure that the student is really paying attention and responding to the visual cues.
Some humans can begin the process of responding to a beat if someone helps them feel that beat in the body.
Help the student feel the beat by moving his/her foot to the beat. The student must sit down, relax the ankle, and allow the teacher to grip the shoe and move the foot up and down with the beat of the metronome or some very simple music.