WORTH NOTING ON TV

* FRIDAY

Shirley Horn: Here's to Life (PBS, 10-11 p.m.): If you want to size up a performing artist's importance, one way is to size up the importance of those who take the time to talk about him or her. In the case of jazz singer and pianist Shirley Horn, the names tell the story: Musician Quincy Jones, singer Carmen MacRae, and other admirers discuss Horn's contributions to jazz over the years. For this portrait, the special takes viewers to Horn's home in Washington, D.C., drops in on a performance at New York 's Village Vanguard, and visits a taping session while the title song of her new album, "Here's to Life," is being recorded.

Laughing Matters (Showtime, 10-11:30 p.m.): It's good to see a documentary about comedy that resists the cliche about the business of laughter being no laughing matter. That's true, of course, but this three-part look at comedy in its many guises - past and present - often takes a comic approach to the examination itself, as it runs down the years on stage, in movies, and on TV, and also deals with many other aspects of the form. In the opener (Part 1), for instance, comic Rowan Atkinson explains "visual

humor" by demonstrating it, lapsing into several roles in the process. He shows clips of Chaplin, Laurel and Hardy, Peter Sellers, and others. He also covers comedy partners like Abbott and Costello, Martin and Lewis.

In Part 2 (airing July 30), host Leslie Nelson interviews Eddie Murphy, Gene Wilder, and others about comedy in the movies. The second half of this part explores the world of the TV sitcom. It offers a look behind the scenes at CBS's "Murphy Brown" and talks with title star Candice Bergen and the producer of the series, Diane English.

Part 3, Aug. 13, is the veterans' stronghold, as stand-up comedy is examined through chats with Bob Hope, Milton Berle, Johnny Carson, and younger stars like Robin Williams and Jerry Seinfeld. The second section of this final program takes a sometimes tongue-in-cheek look at taste in comedy, with a commentary by John Cleese and performances by several comics.

Please check local listings for both these programs.