Many older jazz musicians view the commercial music industry as a fortress with a large potential audience locked inside -- and themselves locked out. Most of them see rock 'n' roll as the ruler of the fort, and distrust the electric guitar as the sentinel's weapon.

But younger musicians realize that the electric guitar can break holes in the wall. Joni Mitchell and Steely Dan have used it to punch their way out; Pat Metheny and Jaco Pastorius have used it to punch their way in.

These younger jazz and rock musicians often have led rock audiences to discover the great jazz musicians. Joni Mitchell has done just that. She collaborated with jazz legend Charles Mingus on several songs that she recorded on "Mingus" with three-fourthsof Weather Report last year.

She then launched a national tour with a young all-star jazz band. Weather Report's bassist, Jaco Pastorius, and veteran drummer Don Alias were retained from the studio band. The Pat Metheny Group's Lyle Mays and Metheny played keyboards and guitar. Michael Brecker -- the younger half of the Brecker Brothers -- played tenor sax.

The Santa Barbara stop on that tour has been realeased as two-record live album, "Shadows and Light" (Asylum BB-704). For the first time, Mitchell's musicians create nuances as subtly as her lyrics do. Metheny and Pastorius stand out in particular. Their strings crackle and fade like an electric storm over the dry landscape of Mitchell's voice.

If Mitchell has given her fans encouragement to go halfway into jazz, now Pat Metheny and Mike Brecker are giving them good reason to go the rest of the way. On Metheny's new album, "80/81" (ECM-2-1180), he and Brecker are joined by three older jazz legends: drummer Jack DeJohnette, bassist Charlie Haden and saxophonist Dewey Redman.

Haden once played with the revolutionary Ornette Coleman Quartet and Keith Jarrett's best quartet. DeJohnette played with Jarrett in the Charles Lloyd Quartet and in the Miles Davis' "Live-Evil" band. All three are uncompromising acoustic players known for their technique, musicality and adventurousness.

Metheny's project was so inspiring it quickly grew from a single record to a two-disc set. The music is exceptional. The Haden/DeJohnette rhythm section swings steadily but maintains the rare flexibility to vary the mood from measure to measure. Seldom has a rhythm unit sounded so melodic.

The most striking aspect of this record is how hard the musicians seem to be listening to each other. No one falls into a steady groove; everyone plays probingly, expectantly. Metheny will try out a phrase and pause for a musical response. Then he will repeat the phrase, taking it a bit further in a slightly different direction. Each of the five musicians is constantly testing and adjusting.

Metheny and Haden both grew up in rural Missouri, 40 miles and 17 years apart. They each composed half of "Two Folk Songs," which occupy side one as the album's most appealing, accessible cuts. Metheny's acoustic guitar strumming and Brecker's bluesy sax solo create the authentic feel of indigenous music.

The older musicians get something valuable in return for contributing their skills and experience: Metheny's graceful compositions. It's no coincidence that the album's weakest cut is a 14-minute uncomposed jam. Each of Metheny's six originals provides a memorable theme and an optimistic spirit for the musicians to work with.

Pat Metheny will appear with Charlie Haden and Paul Motian (former drummer for Keith Jarrett and Bill Evans) at Blues Alley Monday and Tuesday. The original Pat Metheny Group will re-form next spring. Meanwhile, that group's keyboardist, Lyle Mays, will lead his own group at the Cellar Door Nov. 22-23.

Jack DeJohnette has formed his own group of musicians. His New Directions quartet contains trumpeter Lester Bowie from the avant-garde Art Ensemble of Chicago, bassist Eddie Gomez from the refined Bill Evans Trio and young electric guitarist John Abercrombie.

This line-up released a sparking studio album in 1978, "New Directions" and has just released a live album, "New Directions in Europe" (ECM-1-1157). Both albums confirm DeJohnette's insight in forming this strange combination of players.

Gomez creates a gentle, melodic swing. DeJohnette creates a spray of understated, shimmering cymbal taps. Abercrombie darts in and out with his squiggling guitar lines.

Bowie's trumpet cuts across this pastoral landscape like a streaking, silver motorcycle. It's just the right balance of reflection and aggression.