Masks, tape recorders, and other things 'chamber music' is up to these days

Like other art forms, chamber music is going through a lot of changes these days. Some recent directions were on display during a recital the other night at the Third Street Music School Settlement, given as a benefit for the ambitious Music Downtown concert series.

Opening the program, Jon Gibson showed how a single woodwind performer can fill a room with sounds as complex as they are sprightly. The secret is to bring your tape recorder along for accompaniment. While soloist Gibson played alone on the stage, up to eight instruments (all saxophones) chirped from a couple of loudspeakers, weaving pentatonic threads along with his own soprano sax. The result, a 1980 work called ''Extensions,'' recalled the lissome though mechanical structure of Steve Reich's ''Vermont Counterpoint,'' a somewhat similar piece for tape-accompanied flute. Gibson, a remarkably versatile composer, followed it with a tiny waltz of stunning simplicity and appeal.

Reflecting the recent trend toward mixed-media work by composers, Robert Moran then offered a theatrical pastiche. Wearing a gnarled papier-mache mask resembling Richard Wagner, and surrounded by colleagues shuffling around the stage in odd costumes, Moran declaimed a deliberately demented monologue from a massive work called ''Beloved Redeemer Redeemed'' (with no religious connotations apparently intended), which premiered in West Germany not long ago.

The background music, as self-conscious as the rest of the piece, was a taped drone spiced with snippets of Wagnerian chords. The work is aimed at reconciling Wagner's sublime music with what Moran regards as his ''insufferable'' personality. It's part of a trilogy on people he labels ''fascists,'' beginning with Hitler and ending, he says, with Walt Disney.

The evening ended with Philip Glass performing his sturdy Fourth Series organ solo, also called ''Mad Rush,'' and an organ transcription of the fourth ''kneeplay'' from his masterpiece, the gigantic opera ''Einstein on the Beach,'' which is due for a revival at the Brooklyn Academy of Music at the end of next year.

The current calendar of events for the Music Downtown series continues through May 7, with events as diverse as children's concerts, jazz, and a ''Brahms Bash'' celebrating that master's birthday in May. Meanwhile, both Glass and Gibson will be touring in April with the Philip Glass Ensemble, one of the most exciting chamber groups on the music scene. The tour will range from New York to California, including lectures and performances.