The music of the future will be heard largely through loudspeakers, and a lot of it will be -- is already being -- composed for that medium. So said Washington composer Lawrence Moss last night at the tiny, elegant Strathmore Hall Arts Center on Rockville Pike, introducing a concert of his works that vividly illustrated his point.

Moss, known primarily for intricate, intensely crafted nonelectronic works, presented four multimedia pieces composed in the last two years, all involving a sound track in combination with another element. Two works, "Song to the Floor" and "That Gong-Tormented Sea," had taped scores interpreted by choreographer/dancer Alvin Mayes of the University of Maryland faculty. "V/Aria" for viola and tape included violist Richard Field of the Baltimore Symphony Orchestra, and "Installation . . . Lament" was a short film, with a sound track by Moss, acted and scripted by poet/performance artist Yvonne Pickering Carter of the University of the District of Columbia.

This kind of interaction is probably also a firm trend; as Moss observed, audiences seem to have little enthusiasm for sitting in a concert hall and watching loudspeakers. A live visual element also adds flexibility, unpredictability, even the chance of disaster, which are among the attractions that lure audiences to concert halls when they could be home listening to records.

Mayes contributed two smoothly developed, expressive and not specially adventurous performances, which were intentionally not closely coordinated with the music's gestures. Field, using a score written in the traditional style, provided the only purely musical event of the evening. It was a continuously developing set of variations (on a theme announced by the tape with the sound of a viola) that grew increasingly elaborate and frenzied in the viola while the sound track moved from natural to synthetic sound. It was vintage Moss, and a fine addition to the repertoire of an instrument that does not have enough of the solo music it deserves.

In the purely electronic pieces, the musical values were also high, as they are generally in Moss' work. "That Gong-Tormented Sea," in particular, evoked with skill the images implied in the title, and the "Installation . . . Lament" sound track sharpened significantly the impact of the surreal stop-frame visuals and the Gertrude Steinish text.