Two programs show off legendary voices. Jon Vickers as `Otello' and Jessye Norman in Wagnerian role

Two events coming up - one on television, the other on radio - show off two current operatic legends and their particular splendors. Jon Vickers can be seen on the ``Great Performances'' presentation of Verdi's ``Otello'' (PBS, Friday, 9-11:30 p.m., simulcast in many cities - check local listings).

Jessye Norman sings the role of Elisabeth on the Metropolitan Opera radio broadcast of Wagner's ``Tannh"auser'' Saturday afternoon, beginning at 1:30 EST (check local listings).

The ``Otello,'' taped in 1974, is being seen on American TV for the first time. Based on Herbert von Karajan's Salzburg Festival production, it features Vickers in one of his greatest roles and Mr. Karajan in the dual role of stage director and orchestra conductor.

The ``Tannh"auser,'' conducted by the Met's artistic director, James Levine, is familiar to regular Met broadcast listeners, though it will offer them a chance to hear Miss Norman in her first Wagnerian role with the company. Unfortunately, the visual impact of a Norman performance will be missing, but her majestic, sensitive way with the music makes a date with the radio an imperative to anyone interested in great Wagnerian artistry.

The ``Otello'' movie offers all the problems of filmed opera - singers mouthing, often lamely, to a pre-recorded sound track and a certain stilted quality to those scenes that try to re-create livid reality, such as in the opening storm. But Karajan's ``Otello,'' unlike the recent Franco Zeffirelli extravaganza on view in various movie houses across the land, respects Verdi.

The celebrated Austrian maestro may not be the most inventive of stage (or film) directors, but his every idea comes out of the music. He demands that the music be allowed to sustain, support, and further the action.

At one especially fiery moment in the third act, Karajan has the camera focus mainly on Otello's hands clutching Desdemona's wrists as the orchestra rages on. He does not allow his singers to emote needlessly, choosing rather to let a glare do the work of a face distorted in rage. Once one gets used to the restraint, it becomes clear that it complements the music, rather than adding a layer of distractions. At no point does Karajan treat this as anything less than the Verdi masterpiece it is.

This is the exact opposite of the Zeffirelli movie, in which the director tries to improve on Verdi and in the process butchers Verdi's score with merciless cutting, shocking reordering of musical sequences and even the addition of inappropriate music specially written for the film. (Karajan makes two annoying but once-standard cuts.)

Karajan is fortunate to be working with one of history's finest Otellos. And while Vickers was not in optimum voice, the vocal power, the force of personality, and the sheer animal menace of his heroic interpretation combine to make a characterization terrible in its fury, heart-rending in its fall.

Mirella Freni is the touching, elegantly sung Desdemona (only occasionally pushed to her vocal limits), and Peter Glossop a gruff Iago. Karajan's view of the score is conceived on Vickers's grand scale; his reading revels in the music's glories and never stints on the passion and drama. If the sound track of the film sounds anything like the recording released in the mid '70s, it should be one of the highlights of the operatic television season.

The ``Tannh"auser'' broadcast will serve mostly as a Norman and Levine showcase. Happily, Levine's reading has lost none of its fire, tenderness, and sweep. He conducts the singers, reacts to and with them, and exploits the particular beauties of which his Met orchestra is so impressively capable. Otherwise, the cast, as heard on the first night of the seven-performance run, is honorable, but not much more.

In the title role, Richard Cassilly husbands his resources well, but he was unable to deliver the heroic, ringing-toned sort of performance that was his to command three seasons ago. Eva Randova's Venus is rather too small scaled for the house, but it is sure and even powerful in its textual declamation; Haken Hagegard's Wolfram has improved since the last time around, without being at any moment completely up to Met standards; debuting bass Jan-Hendrick Rootering makes a passable, if vocally underweight, Landgrave.

Norman, therefore, dominates totally. Her voice proves enormous in the theater, especially in the lower two thirds of the instrument. She, too, is a superb declaimer of text; the words thrust out with clarity and an unerring sense of the emotional weight and content of each syllable.

As we have come to expect from this unique artist, it is a performance entirely her own, done her way to suit her instrument, and yet utterly faithful to Wagner and the grand tradition of Wagnerian singing that has been the particular pride of the Met throughout most of its 104-season history.