Navy Vice Adm. Bobby Ray Inman, the soft-spoken superstar of the U.S. intelligence community, won quick and unanimous approval from the Senate Select Intelligence Committee yesterday as President Reagan's choice to be deputy director of the CIA.

Earlier in the day, the Senate Armed Services Committee endorsed a presidential recommendation for a fourth star for the 49-year-old officer, which will place Inman among the youngest full admirals in Navy history.

Inman, with 28 years in the Navy, much of it as an intelligence officer, has won widespread acclaim within the government as the director of the supersecret National Security Agency (NSA), which he has headed since July 1977.

Inman wanted to stay at the NSA rather than move into the deputy's job at CIA, and he told the Intelligence committee yesterday that he was appearing before it as something of a "draftee." Committee Chairman Barry Goldwater (R-Ariz.) told Inman the he had urged CIA Director William J. Casey to go after him for the No. 2 job because, Goldwater said, he "didn't know a man in the business who was more highly regarded."

Sen Jake Garn (R-Utah) said Inman was "the most direct and forthcoming witness" to come before the committee in recent years and praised the admiral for "never hedging his opinions or worrying about politics." Inman's directness and knowledge are the characteristics that have won him so much praise. The admiral tried to take it in stride yesterday, telling the panel members that "I hope we'll both feel at the end of two years that it was the right choice."

The NSA director presides over some of the nation's most sensitive communications monitoring and code-breaking equipment. But at the CIA the intelligence chores are even broader. Under questioning by the committee yesterday, Inman said he was worried most about the manpower problems in the intelligence community.

For a variety of reasons -- some related to the costs of Vietnam and the expense of equipment -- intelligence manpower levels, particularly the number of experienced analysts, have steadily eroded over the last eight years, Inman said, adding that he hopes for some "redress" despite the federal hiring freeze. He said it was vitally important to have more analysts who understand cultures, religions, politics and economics and who speak languages. There is simply no substitute for that in terms of making sense of the information gathered, he said.

Inman believes there is a "generation gap" in the intelligence community caused by the retirement of officials who joined in the post-World War II era. He said there was a need for keeping specialists in the same job without sacrificing their promotion prospects. The U.S. capability for understanding foreign languages and cultures "is poor and getting worse," he said, as there are fewer Americans who speak a second language at home.

Pointing out that there are many young people with the aptitude to learn languages, but that it takes years of training, Inman said one of his jobs will be to improve ties with the academic community. He suggested the intelligence community might have to find ways to recruit and train language students, even if it requires sponsoring programs in universities.

Inman said current U.S. intelligence capabilities are "outstanding" when it came to counting things, such as enemy missiles, by technical means and "very impressive" in terms of providing warning time. But in assessing trends, U.S. agencies do less well. There are areas of the world where problems often develop rapidly and where there is scanty intelligence collection, he said.

Though Washington has a "fairly significant lead" over Moscow on the technical side of data collection, the Soviets apply about three times as much manpower to solving intelligence problems, Inman said. The admiral said the best U.S. intelligence capability is in the military field and that it comes from higher standards forged by competition. Inman said he would "urge strongly" against any move to consolidate intelligence analysis among the various agencies.

In response to a question, Inman said the suggestion, which occasionally surfaces in the press, that the U.S. intelligence community overestimates the Soviet threat to push for higher military budgets is "flatly wrong."

On "rare occasions," he said, intelligence assessments have overestimated Soviet strengths, but on many more occasions, he said, the U.S. estimates have proved to be too conservative.