BOB ABERNETHY: Klezmer, rooted in the Jewish religious tradition, has become very popular. Based on East European Jewish wedding and folk music, klezmer is being played in concert halls, trendy nightclubs, and on festival stages throughout the world. And it's not just Jews who are listening. Music critic Seth Rogovoy reports about klezmer's growing popularity. The first voice is Hankus Netsky of the Klezmer Conservatory Band.

HANKUS NETSKY (Klezmer Conservatory Band): The reason the music is so popular is that it has a beat that you just can't ignore, and it literally makes people get up, out of their seats and dance.

SETH ROGOVOY: Klezmer, which means "vessel of song," has evolved from the instrumental dance music played at Jewish weddings and celebrations. The melodies were often borrowed from traditional prayers and songs, and influenced by East European ethnic music. Klezmer is played in a distinctive melodic mode that sounds happy and sad at the same time.

MR. NETSKY: You don't just play, and play notes, you have to feel it. It's definitely all about expressing your feelings, very often feelings of pain, feelings of yearning, which are part of even the happiest piece.

ROGOVOY: Klezmer also has a spiritual dimension greatly influenced by Hasidism, a popular mystical movement born in 18th-century Eastern Europe.

MR. NETSKY: In Hasidic culture music is so important. In fact, to write a beautiful melody is to in some way heal the entire universe; to play a song with the right intention is so important because that will give the song special power. The entire way that a composition is looked at in Hasidic music is about a spiritual awakening.

ROGOVOY: While today's klezmer is sometimes combined with influences from jazz, rock, and world-beat music, it is still characterized by the sound of the wailing clarinets and violins. The musicians bend and twist notes to evoke the sound of the prayers chanted by a synagogue's cantor, which produces the laughing and crying quality of klezmer.

Listen to "Klezmer à la Bechet" from David Krakauer's latest CD, A NEW HOT ONE.

DAVID KRAKAUER (Klezmer Madness): I think that's what makes klezmer music so special, and the klezmer clarinet, because it is really the sound of the cantor, the sound of the Yiddish language. When I first started to play klezmer, I had this instant recognition: Oh, that's the voice of my grandmother.

ALICIA SVIGALS (Klezmatics): The way the instruments play and imitate the cantor's voice is so strongly Jewish that it feels like religious music even when it's not.