When Washington attorney Jean-Pierre Swennen checked into the Howard Johnson Motor Inn at Newport News, Va., he carried a suitcase, a briefcase, and what suspiciously looked like a violin case. His only request to the desk clerk was for a "room far away from everyone else."

Swennen, once settled, carefully removed a new violin from its case and with an unusual amount of eagerness began to practice scales. After 15 minutes of "playing," he suddenly heard a woman's voice in the hall shouting expletives and screaming, "I can't stand it anymore!"

"I was stunned," recalls Swennen, 40, a serious, handsome man who looks like a concert violinist even though he doesn't (yet) play like one. "I immediately ceased operations and just sat on the bed in silence. Five minutes later, I put a mute (metal silencer) on the bridge of the violin and continued playing. It was an embarrassing lesson. Now I never practice my violin on a business trip without using the mute."

In a year's time, with faithful practicing at home and on trips, Swennen's "squeaks and squawks" on the violin have graduated to far sweeter sounds based on Beethoven and Mozart works which he has "always loved and wanted to play."

Swennen is one of the growing number of adults in this country learning to play musical instruments "for the sheer pleasure of it": an unexpected trend which could say something about a need for diversion during these economically perplexing times.

"We experts are amazed and mind-boggled by this trend, which is definitely nationwide," says Joanne Hoover, director of Washington's Selma Levine School of Music, where 60 of their 300 students are 30 to 60 years old.

"These adult students know they won't master the instrument, or take it up professionally, yet why shouldn't they learn to play?"

Hoover feels that when you look at the ages, backgrounds, physical limitations and the full lives of these older students, "you can't help but admire them. It is such an act of courage, it's a triumph of the human spirit to even attempt it."

Mid-life music students often talk of "shaking like a leaf" before the first lesson. One 43-year-old man who took up the piano for the first time said his first meeting with his teacher and the keyboard was more frightening than when he gave his oral dissertation for his doctorate.

"Their expectations are always less than their capabilities," says Mark Ellsworth, 68, the founding father of the popular Ellsworth Studios in Bethesda, Md., where one-quarter of the 700 students are adults, a sizable jump from previous years.

"These students immediately tell their age when they first call," observes Ellsworth. "One 58-year-old man talked on the phone for over a half hour, insisting his fingers were too large to play a violin. When I finally convinced him to come in for a consultation, I could see his little finger was as big as my thumb. He was a kitchen installer who had done hard work with his hands for years. Yet, in three years he was playing the violin in a church orchestra in Georgetown."

Some students start cold with no previous musical training. More typically, many took piano or violin lessons as children and remember well how much they hated the instrument, the teacher and most of all, the practicing. As adults, they may return to the same instrument, or decide on another, but ironically, they no longer have qualms about practicing: They even welcome it. Perhaps, says Ellsworth, because they've now learned to manage complex scheduling at home and on the job and it's no longer Mother saying "It's time to practice." Now it's self-discipline.

Families with older children may find a parent's practicing a double bonus: Al Sanoff, 40, a national magazine writer who lives in Bethesda, Md., has taken up the saxophone--"I've always liked the jazz of Paul Desmond and Stan Getz"--and when he practices his scales each evening after dinner his two older boys practice their violin and viola "without any complaints."

Traditionally, a child's motivation for practice is the notorious "recital" where parents, relatives and willing friends gather to applaud, bite their cheeks, take pictures and decide if the music lessons are paying off.

Former Sen. George McGovern, 59, gave his first piano recital for his friends and the media after only six months of lessons, because that's what his teacher "requires of all his students." Fortunately for McGovern and for all who attended, he played admirably and no one had to pretend to enjoy it. But most music teachers feel the recital is "unnecessary" and "too much to ask of anyone over 30"--a relief to those constantly concerned with "performance" in their jobs.

"Our students are successful people in stress-filled jobs," says Mark Ellsworth. "We have research scientists, physicians, lawyers, who have a great deal of interest in succeeding in music, as they do in their professions, but we have to prod them into a recital." His solution: a relaxed concert on April Fools Day when students can invite family "if they want to."

David Ruth, a Silver Spring piano teacher in his early 50s, now teaches only adults since he discovered two years ago "They are more fun to teach than children."

A Juilliard graduate, Ruth's current teaching "has borrowed heavily" from the Suzuki method which he studied specifically to see how it could be applied to adults. In Suzuki, the young child learns difficult pieces by constant exposure to model sounds. Ruth believes that adults already carry in them melodies they remember and love even though they can't recall the title or the composer. He may ask a new student to pick a favorite melody, then for the first few lessons they work only on hand and finger coordination until the melody can be recognized and enjoyed. In time, the student puts his own feeling, "his soul" into it.

"One of my students picked out a Beethoven melody with his second finger, a tune he had loved since he was a child. It was a shame he waited so long to express it, but in time he learned to play it well, and it meant a great deal to him."

One of Ruth's favorite students is Pat Durkin, a reporter for a weekly newspaper. "I convinced my parents last year to let me have the piano I grew up with. I had taken lessons when I was 8 and hated it," says Durkin, now 39. She is delighted to have the piano in the corner of the dining room, vying for attention with her three children.

"I don't have a strong musical background, but I love music and over the years it has become a language in (my) head, and it has to be expressed. It's expressing language in a totally different way, not a repetition of what's been played or composed by someone else, but with my own expression. I just had to take lessons."

Such motivation and introspection is not uncommon:

Swennen explains his determination to play the violin as one "constructive way to deal with mid-life crises" where there is "a release of a different energy" and a need to "direct the energy in a creative way." A practical man, he also considers the time spent learning the violin as his "personal Keogh plan" which assures him a pleasurable pastime during his retirement years.

"I've tried mountain climbing, skiing, even gliding. I can't do those things when I'm 70, but I can always play my violin."