During final exams in the spring of his first year of medical school, Cesar Servellon awoke one morning with a ringing sensation in one ear.

By the middle of his third year at the University of Wisconsin medical school, when Servellon was preparing for a hospital internship, his hearing had deteriorated so much that it was impossible for him to talk on the telephone or understand what was being said in meetings. The sudden, unexplained hearing loss was a mystery to his doctors, and for a while Servellon feared he would have to forgo his dream of being a physician.

"People said, 'You cannot consult with patients; you cannot call to get a lab report,' " he recalled this week.

Servellon, a 33-year-old native of El Salvador, is profoundly deaf now and cannot hear speech. His hearing loss is still unexplained.

But despite his initial despair, he has not given up on a career in medicine. Servellon is now a first-year resident at Prince George's General Hospital, and he hopes to become a psychiatrist specializing in treatment of the deaf.

There are only about eight deaf physicians and two deaf psychiatrists in the United States, according to the American Association for the Advancement of Science.

Initially, Servellon said, the impact of his hearing loss staggered him.

"Music was out, conversation in groups was out, theater was out -- you're just trying not to lose your mind," he said. Then he began to use sign-language interpreters, and, he said, "my life began to light up."

He was able to finish his course work in Wisconsin and go on to rotating hospital internships last year at Georgetown, George Washington and the National Institutes of Health. Servellon was turned down for a residency by every other hospital he applied to, but Prince George's General officials said they saw him as a top recruit, despite his deafness.

"His grades and recommendations were excellent," said Dr. Rishpal Singh, who helps select residents for the hospital and oversees their training. "I was very impressed with his courage and determination to succeed."

Prince George's General officials are so committed to helping Servellon get through the residency program that they have taken the unusual step of paying $30,000 a year for a sign-language interpreter to accompany Servellon full time. While an intern and in medical school, Servellon's interpreters were paid for by the state of Wisconsin.

Servellon, a resident of this country for 14 years, has long been fluent in English. He speaks directly to the patients and is proficient at lip reading. What he does not understand is quickly signed to him by his interpreter.

Monday morning, Dorothy Kersey, a Hyattsville resident happy to be going home after 10 days in the hospital's cardiac rehabilitation unit, joked and chatted amiably with Servellon as he examined her.

With Servellon keeping an eye on his interpreter standing nearby, conversation between Kersey and Servellon flowed easily. In fact, Kersey scarcely seemed to notice that her doctor was unable to hear her.

Unlike some other deaf physicians who have gravitated to fields in which patient contact is limited, Servellon wants to go into psychiatry, where communication is everything. He has the confidence of the doctors who have come to know him in the last month at the hospital and during internships last year.

"He has an extraordinarily caring personality; he shows unusual warmth as a physician," said Dr. Barry Epstein, chief of the hospital's department of medicine.

John Fletcher, chief bioethicist at the National Institutes of Health, where Servellon did a two-month internship in psychiatry last year, is convinced Servellon will be a skillful psychiatrist. "After meeting him, I was persuaded very quickly he could do it," said Fletcher, whose parents are deaf.

Servellon, who came to the United States to attend college and never moved back home, said, "All the memories I have of San Salvador are memories of war." He graduated from Florida International University, got a master's degree in biochemistry from Georgetown, then went on to medical school at Wisconsin. A bachelor, he lives in Southwest Washington.

Servellon said he believes his deafness will make him particularly effective in dealing with deaf psychiatric patients. He will not need a sign language interpreter as many hearing psychiatrists would, allowing him greater intimacy with patients.

In addition, said Servellon, "You really have to know about deafness in order to understand deaf individuals." He thinks he will be more attuned to the nuances of sign language communication, and will better understand the isolation from the hearing world felt by many deaf people, he said.

Things get tricky for Servellon -- and for his interpreter -- when he is with other doctors. During rounds with other residents and physicians on his medical team, for example, there are often several people participating in discussions, all using medical terms that the interpreter must furiously rush to spell out because no signs exist for those words.

Servellon is uncertain about whether he will be accepted into a psychiatric residency program next year. He said officials at some hospitals have been skeptical of his chances because they believe it would be difficult for him to work with hearing patients while he is in training.

Servellon has found ways to cope in the hearing world. He is frequently required to talk on the phone, for example, ordering a laboratory report or answering his beeper, which doesn't actually beep at all but vibrates silently. With the help of his interpreter, who listens in on an extension and signs to him, Servellon is able to conduct telephone conversations in a way that sounds entirely normal to anyone on the other end.

On Monday, in fact, Servellon sat in the nursing station outside Kersey's room and discussed Kersey's case in a conference call with her primary physician and her nurse. Midway through the conversation, Servellon told the other doctor why his interpreter, who had spoken up briefly, was also on the line. "I am deaf," he explained to the surprise of the other doctor.

Deafness may mean some hospitals "slam the door on you," Servellon said, but he also said he had had help from the medical community. A deaf family practitioner in California showed him how to use his hands and a visual instrument called an oscilloscope to "listen" to a patient's heartbeat, he said, and administrators as well as his peers at Prince George's General have received him warmly.

"I am lucky to be here," he said.