One of the interesting things about the rock industry in the last few years has been the erosion of the merchandising dominance of the 12-inch album and seven-inch single. In part, the current industry slump and the high cost of introducing new acts have forced companies to look for cheaper approaches. In the last year more and more record companies have begun using the 12-inch, five- or six-song EP as a means of giving the record-buying public a meaningful earful of a musical newcomer, while keeping costs and the record's retail price way below those associated with an album. While this may be efficient, when an EP is as artistically impressive and emotionally engaging -- as are new ones by T-Bone Burnett and R.E.M. -- the listener is left feeling about five or six songs short.

While Burnett is somewhat unknown to the record-buying public, this enigmatic Texan has had a notable history including a guitar slot in Dylan's Rolling Thunder Revue, three albums of curious musical exoticism as a member of the Alpha Band, and one critically acclaimed solo album, "Truth Decay," that may have been 1980's best rock album. Simply stated, his new six-song EP, "Trap Door" (Warner Bros., 23691-1B), may be the most profoundly elegant and powerful rock release of 1982. Burnett's parabolic songwriting and ironic delivery, the grandiose Tex-Mex flourishes of his band and its ominous bass drum dynamics, and David Mansfield's lyrically romantic guitar passages result in rock 'n' roll of unusual intellectual and emotional depth. If Dylan is the only relevant comparison, you would have to return to "John Wesley Harding" for a comparable experience.

There is only one cover here, but Burnett's reading of Leo Robin and Jule Styne's classic, "Diamonds Are a Girl's Best Friend," is a minor revelation. The song is marvelous not only because Burnett's sardonic reading of the lyrics elevates the tune to a biting piece of anticapitalism, but because with one sublime phrase, "let's rock," Burnett shatters the tension as his band joyously releases into a gently rocking rhythm break. There are no misses here. In the ringing and melodic guitar sweep of "Hold On Tight," the Lennonesque critique of a "Ridiculous Man," the elegiac hymn called "Poetry," and the mystically foreboding "Trap Door," you sense that Burnett is addressing that whole generation that became spiritually unanchored in the '60s and is still seeking a place of emotional refuge in the '80s. Burnett may not sound like fun, but his music offers the most uncommon of rock 'n' roll satisfactions, those that come from leading the listener deeper into himself.

R.E.M. follows the B-52s, Pylon and the Method Actors as another young band making national waves out of Athens, Ga. However, the group's mastery of '60s, guitar-based pop strategies and the modernist undercurrents it employs to revive those strategies places it among contemporaries like the Bongos and the DBs. All twist conventional power-pop playing away from the territory of commercial radio to more esthetically compelling realms. On its five-song debut, "Chronic Town" (IRS SP70502), there's no doubt that this four-piece band recalls the folk-rock stylings of the Byrds, Big Star and others. Yet this band, which will appear at the 9:30 club in late November, is distinctively spooky without being downbeat and refreshingly ambitious without giving way to affected experimentalism.

R.E.M. songs are all characterized by Pete Brick's shimmering Rickenbacker chords and Mike Mill's strained, dream-like singing. Although the songs are melodically incisive, with haunting choruses repeated over and over, they're hard to understand. "Carnival of Sorts" is typical; the band strings surrealistic images in and out of explosively shifting rhythms that give way to an ecstatic chorus, "Boxcars are turning, out of town." Like its music, the band's lyrics carry the sense of anxiety that arises when the familiar is jarred and something eerie and unexpected, yet attractive, asserts itself.

The Blasters, Los Angeles' celebrated, hard-nosed rock 'n' roll band, isn't really an unknown commodity. The release of its six-song EP, "Over There: Live at the Venue, London" (Warner Bros. 23735-1B), is less designed to attract new buyers than to keep its rapidly growing legion of fans happy while awaiting a new album of original compositions. Five of these live cuts are covers that showcase the furious, pounding sound the group has evolved, but obviously add nothing to the Blasters' reputation as the only traditional rock band that can write great '50s-style rockers (courtesy of guitarist Dave Alvin).

The highlights of this EP are the band's breakneck versions of Little Richard's "Keep-a Knockin' " and Pete Johnson's "Roll 'Em Pete." The latter is a showcase for pianist Gene Taylor's boogie-woogie stylings, while the former allows legendary saxophonist Lee Allen to reprise the screeching solos he played on the original 25 years ago. The least successful cover is of "High School Confidential," a rock 'n' roll vehicle so loaded down with the unmistakable humor and frenzy of Jerry Lee Lewis' distinctive piano and vocal style that it really can't carry any new passengers. In all, this is just a party record from a rock 'n' roll band that has always promised party and then some.