During Armen Ra’s last concert at the Gershwin Hotel, a concert audience sat transfixed at the sight onstage. Wearing heavy makeup and a simple black evening dress, the Armenian Mr. Ra stood in front of an odd machine with protruding antennae, his outstretched hands trembling, causing a weirdly compelling wailing, recognizable as tunes by Bizet, Chopin, and Puccini. “I also throw in things like the ‘Laverne and Shirley’ theme song,” Mr. Ra said to one interviewer.

This unexpected mix of repertory is only the latest bump in the curious trajectory of the theremin, a pioneering electronic instrument invented in 1919 by Soviet physicist Leon Theremin. The theremin contains two antennae, one regulating pitch and the other volume. As the performer’s hand nears the vertical antenna, the pitch — or audible sound frequency — is raised. Getting closer to the horizontal antenna with the other hand lessens the volume. No direct touching of the antennae is involved, which makes the theremin require precise gestures from performers, and an unerring musical ear. The sound emitted is a wide-vibratoed wail, penetrating and ardent, like a liquidly flowing, steroidal cello, mixed with the piercing high tones of a violin or a child in distress.

Live performances and new CD releases are adding new dimensions to the instrument. Many music lovers still think of the theremin — if they think of it at all — in terms of the 1966 Beach Boys hit “Good Vibrations,” which used a simplified version of the instrument, or the soundtracks of sci-fi films, like composer Bernard Herrmann’s sounds for alien invaders in “The Day the Earth Stood Still” (1951). In fact, Dmitri Shostakovich was the first screen composer to use the theremin, in a 1931 Soviet film, “Alone,” in which a hysterical heroine is lost in a blizzard. Hollywood followed suit, embracing the theremin in overwrought film scores by Hungarian-born Miklós Rózsa (1907–95), who evoked eerie mental torment in Alfred Hitchcock’s psychological thriller “Spellbound” (1945), starring Gregory Peck.

Yet Theremin himself had more lofty intensions for his instrument and trained early disciples with roots in classical music, notably the Lithuanian-born virtuoso Clara Rockmore (1911–98), born Clara Reisenberg. “Clara Rockmore’s Lost Theremin Album,” a CD of previously unpublished 1975 recordings of Bach, Schubert, Chopin and other classics by Rockmore, has just been released by Bridge Records. These recording sessions were instigated by theremin fan Robert Moog (1934–2005), another electronic music pioneer, who invented the Moog synthesizer.

The weeping and sobbing theremin is best partnered with string instruments, like a group of cellos in an arrangement of the aria from Villa-Lobos’s “Bachianas Brasilieras No.5,” or Ponce’s popular “Estrellita,” accompanied by the Argentine guitarist Jorge Morel. The percussive hammers of a piano, albeit played with utter sympathy on the Bridge CD by Rockmore’s sister, the noted piano teacher Nadia Reisenberg (1904–83), sound mismatched with the quivering waves of sound.

Restricted for decades to either high or low culture, the theremin waited to be rescued by a new kind of contemporary music that united both cultural extremes. Today’s generation of avant-garde composers is comfortable with electronica, like the young Russian composer Lera Auerbach, who wrote a ballet score, “The Little Mermaid,” in 2005, featuring the theremin as the mermaid’s voice. The theremin soloist at the world premiere at the Royal Danish Ballet was Lydia Kavina, who has just released “Touch Don’t Touch — Music for Theremin” a CD of new works on the Wergo label, distributed in America by Harmonia Mundi. Ms. Kavina was a protégée in Russia of Theremin himself, who survived long enough to star in a worshipful 1994 documentary, “Theremin: An Electronic Odyssey,” directed by Steven M. Martin. On the new Wergo CD, Ms. Kavina plays with one of her students, the German virtuoso Barbara Buchholz. “Canto Ostinato for Two Theremins, Piano, and Percussion,” by the young Moscow composer Olga Bochihina, is spare and vulnerable like one of Webern’s lonely-sounding miniatures. “Theremin Islands for Two Theremins, Piano, and Percussion” by the German composer Nicolaus Richter de Vroe captures the isolated, mutant quality of the instrument.

More vibrant affirmation of the instrument’s enduring creative potential is offered by a slew of ardent players, from Japan’s Masami Takeuchi, another Kavina student, to Pamelia Kurstin, born in Southern California and now living in Austria. Ms. Kurstin has performed with David Byrne and Béla Fleck and is working on a solo theremin CD for the saxophonist/composer John Zorn’s record label, Tzadik.

And while rock musicians retain affection for the theremin, today’s models of synthesizers are easier to play and can mimic the sounds of the older instrument. Project: Pimento, a five-piece San Francisco ensemble, presents itself as a “theremin-fronted lounge music band,” whose debut CD, “Magical Moods of the Theremin,” came out not long ago. The band’s leader, Robby Virus, played theremin on the soundtrack to director Guillermo del Toro’s 2004 sci-fi fantasy, “Hellboy.” Disparate groups that have used the theremin include Led Zeppelin, Simon and Garfunkel, Aerosmith, and Mötley Crüe. Some theremin soloists continue the dignified Clara Rockmore tradition; in August, “Vocalise,” a new CD by Masami Takeuchi appeared, featuring pristine performances of works by Tchaikovsky, Fauré, and Mozart. Yet other players and composers look likely to keep Theremin’s invention permanently surprising. Those still in doubt might wish to attend Mr. Ra’s sober concert at the Gershwin Hotel on April 24.