Sholom Katz can't express himself well in words. His metier is music - Jewish liturgical music, because he is a cantor. When he talks about his love for America, his phrases sound like cliches written by the America First Committee.

It is a while before you realize that he is not repeating a well-memorized script. Then you learn that 35 years after the holocaust he still wakes up at night screaming, dreaming that he is back in the concentration camp.

Although, he wants to talk only about America, Cantor Katz always talks about it in opposition to the horrors of the Europe he knew.

"This country is different. The freedom . . . if you are not satisfied you can say it. If you ever lived under tyranny then you know the difference . . . even the air is different," he says.

Katz, who arrived in Washington from Rumania 30 years ago to become cantor for Beth Sholom Congregation has become one of the best-known cantors in the United States. He has made more than 160 records of Jewish music, has sung all over the country and in three movies - "Garden of the Finzi-Continis." "The Eichman Story" and a BBC production, "The Warsaw Ghetto."

The cantor, who left Beth Sholom 20 years ago, also works in the Catskill resort of Kutschers, where he sings for all major Jewish holidays.

When he was honored by the Jewish Ministers and Cantors Association of America in New York earlier this year, Cator Katz received letters from several national leaders.

President Carter wrote: "Rosalynn and I send you our warmest personal regards."

"You survived the devastation and misery of Jewish persecution in Europe to enrich the religious heritage of an adopted and grateful homeland," wrote Hubert Humphrey.

The cantor received letters of congratulation from other prominent figures, including senators Edward M. Kennedy, Abraham Ribicoff and Henry Jackson.

"Would another president or king send a cantor a letter like this?" Katz said. "Even though I have suffered so much. America has paid me."

The Cantors Association of Greater Washington, of which he has been president for the last six years, held a dinner in Katz' honor recently.

A child prodigy in his hometown in Rumania. Katz was a recognized cantor by the time he was bar mitzvahed at the age of 13. He went on to study in Vienna with one of the great teachers and to become cantor for one of the largest Jewish communities in Europe.

Then the Nazis came, and Katz ended up in a concentration camp. Told to dig his own grave, he asked permission to sing.

He sang the Jewish prayer for the dead so beautifully that a Nazi officer commanded him to sing for an officer's party that night. Katz sang while the other men who had dug with him were being shot. In the morning the officer let him escape.

When the war ended Katz became the chief cantor of Bucharest, where he stayed until he came to Washington.

Within a year of his arrival here, the cantor had met his future wife, who has also a survivor of Nazi concentration camps, and they were married in a ceremony performed by 20 rabbis. The Katzes, who live in Northwest Washington, have two children, a daughter who is in law school and a son who is study accounting.

"I am a big patriot," Katz said. "Someone born in America might feel different, but my love for America . . ." He didn't finish the sentence, because he couldn't find the words to explain why he is appalled by people who criticize the United States as a system of government.

He says he does not want to talk about the Nazi horrors, but he returns to the subject with cryptic stories, like the story of being in hiding with a group of people when a baby started crying, "You know what the mother had to do," he said.

Katz said he feels cut off from people who do not understand. They question and challenge him. He recalled a woman who could not believe that 2,000 Jewish men could be marched out into fields by five Nazis with guns.

"She wanted to know why we didn't rush them. But where could we go? It was winter. We were naked. There was no one we could go to," Katz said.

A few weeks ago the woman came back to him. "Now I understand," she said. She had been a hostage in the B'nai B'rith building when the Hanafi Muslims took over.There were 122 hostages, and three men with guns. "Now I realize what you told me. Now I know what a gun means," she said.

But she can't know, Katz said. If she had gotten away, she would have been in America, where even the air is different.