If you take a look at today's recordsales charts, you're likely to find that the list labeled "Easy Listening " does not differ drastically from the "Hot 100" list -- a chart which used to be considered strictly rock 'n' roll.

When you bring your Valentine over for a candlelight dinner, the music on the stereo is more likely to be the Eagles than Frank Sinatra, because radio stations are playing less and less of what is still refered to as middle-of-the-road (MOR) music, And this homogenization of America's popular-music taste is making a lot of the older-styled jazz vocalists obsolete.

So, you listen to three recent reissues on Bethlehem the way you look at old photographs in a museum: with an appreciation tinged by nostalgia. Chris Connor, Johnny Hartman and Mel Torme are singers whose time has passed, but these recordings -- all done in the mid-'50s -- enable us to hear the sound of a past era. None of the three can be considered jazz vocalists in the pure sense, yet all were heavily influenced by jazz and these albums feature jazz players.

Connor's "Cocktails and Dusk" (Bethlehem, BCP 6010) offers old standards, though she uses musicians like Milt Hinton, Herbie Mann and Kai Winding. The material is heavy on Cole Porter and composers like the Gershwins ("Someone to Watch Over Me") and Alec Wilder ("Trouble is a Man"). The captivating mood of the album is produced by the tension in Connor's voice, a tension that overrides her lack of range and occasional blandness.

These songs were recorded in 1955, when she was receiving some acclaim, and it is easy to hear how she temporarily captured her audience's attention.

Johnny Hartman's "All of Me" (Bethlehem, BCP 6045) benefits and suffers from the same time-based afflictions as Connor's album. Hartman's smooth delivery is reminiscent of Billy Eckstine and Arthur Prysock, but on "All of Me" he never moves from the set patterns of his songs.

Pure jazz singers generally make their names by vocal improvisation, but Hartman is not an improviser. At his most affected, he sounds like comedian Bill Murray's imitation of the Holiday Inn entertainer on "Saturday Night Live."

Yet one must remember that this was the style of post-swing, pre-Coltrane music, and that Hartman never claimed to be a jazz singer. (This is ironic since later Hartman did sing some with Coltrane.) He is a vocalist, and his readings of Irving Berlin's "Blue Skies" and standards like "Birth of the Blues" and "I Get a Kick Out of You," are examples of a performer precisely practicing his craft.

Hartman, like Connor, sounds dated, but this album comes from a period when music stood still longer than it does today. Hartman seems to lack imagination partly because imagination was not considered essential to the mix. The idea here is for the listeners to close their eyes and use their imaginations.

Mel Torme's "The Torme Touch" (Bethlehem, BCP 6042) is a different story. For one thing, Torme is much closer to a pure jazz singer than Hartman. For another, on this 1956 date, Torme worked with a smaller ensemble and was able to bend the songs to fit his vocal style. The composers on Torme's album are in the same vein as those on the Hartman and Connor records: Gershwin, Richard Rodgers, Duke Ellington, etc. It's the approach that changes here.

Torme's upbeat tunes swing, and his ballads employ blue notes and clever phrasings. Torme sounds like a radical, compared to Hartman, when he launches into "Lulu's Back in Town" and "The Lady is a Tramp." His supporting players, led by Marty Paich and including bassist Red Mitchell and reedman Bud Shank, have a big band sound but a smaller group intimacy, and Torme is able to steer them instead of getting himself caught in the arrangements.

Despite these strengths, there are still moments that make you feel that the music really does come from the long, lost past. "Carioca" sounds a bit like the soundtrack to an "I Love Lucy" segment and even Torme's gliding vocal work cannot keep "Fascinatin' Rhythm" from sounding like the old-timer it is.

The feeling you get from listening to all three albums is that the '50s were not a particularly fertile period for popular jazz vocals. But the decade's music had an endearing quality -- possibly because its essence was so easily distilled.