J. Kennth Mathews of Arlington enjoys a good musical comedy. When he was in New York recently, he laid out $48 for two mezzanine seats to "A Chorus Line."

Ken reports, "When the curtain went up, I received a rude shock. There was no pit orchestra. Instead, there were four mammoth speakers that belched out a recorded version of the music. The volume was turned up so high that the sound that came out was enough to burst your eardrums. There was no way to tell whether the principals on the stage were doing their own singing or pantomiming super singers on the tape."

Ken thinks canned music is a poor substitute for a musical comedy's live orchestra. He says that when a musical show doesn't include an orchestra, prospective ticket buyers ought to be advised in advance. All advertisements for the show should reveal that the music will be furnished by recordings.

Ken also points out that one who pays $24 for a seat has a right to expect he will be getting the live performers who traditionally furnish the music that is musical comedy's basic ingredient after all, if there is not orchestra, production costs are lower and ticket prices ought to be lower.

Ken's views are locical enough, and I wish the Federal Trade Commission or some other appropriate agency would require "full disclosure" in theatrical advertising.

However, I do not think there is anyreal hope of enacting such a requirement at this time.Few government regulatory agencies are prepared to act against an abuse until it becomes widespread and gives evidence of continuing indefinitely.

The fact that you feel you've been gypped or I feel I've been gypped does not really interest the FTC. It is not geared to handle individual cases.