The air is alive for a lot of people this weekend, but none, we'd guess, feel it more keenly than the dozen young singers who will be going through the last rounds of auditions for the Metropolitan Opera in the Mid-atlantic Finals, which WETA (91 FM) will be broadcasting live and in stereo Saturday from 2 to 5 p.m.

Now, at the end of two-month competition, each will perform two arias -- one at the finalist's choice and one at the judges' -- and the winner will get something more important than the cash prize: a trip to New York to vie for a contract with the met.

It will be the first live broadcast from the new East Wing's auditorium, and it will be interesting to us -- and crucial to the contestants -- to hear the acoustics of our town's newest attration.

Rose Bampton, who made her Met debut in 1932 in "La Gioconda," will head the panel of judges.

The next day, at 4 o'clock, you can catch a strictly non-bluegrass kind of guitar: an hour of Andres Segovia live at the White Hose, via National Public Radio and simulcast locally by WETA (watch on Channel 26). Then you can catch the same thing again at 8 (WETA again) or Monday at 12:35 on "Measure by Measure" (WAMU 88.5 FM). Does it sound as if they're doing it over and over again until President Carter gets backto hear it?

Actually, of course, Segovia's music is much older than bluegrass: He gave his first recital 70 years ago, at the age of 15.