Klezmer as we now know it was originally just referred to as Jewish music and was played by Jewish musicians in Eastern Europe for several hundred years prior to the Second World War.
After the Russian pogroms, many klezmer musicians (or klezmorim) fled to America, and there, from about 1910, klezmer began to flourish.
After the 1940s, however, the music almost totally died out - devastated in Europe by the death of so many Jewish musicians in the Holocaust, and unable to fight off the rival claims of the folk music emerging from the newly created state of Israel. Klezmer was relegated to a few isolated moments at weddings and barmitzvahs.
The revival started in the late 1970s, led by several outstanding American musicians keen to explore the music of their roots. An upsurge of interest followed in this country, catalysed in 200 by the introduction of KlezFest music festival. Prominent among the groups that emerged were Oi Va Voi and the Sophie Solomon Band.
When you listen to the tracks from the groups entered in Klezmer Idol, you will discover that a klezmer band can mean a lot of different things. Some bands play only instrumental music, some perform only Yiddish songs with a klezmer backing, some play traditional klezmer tunes as close to the original recordings as possible, whereas others combine klezmer sounds with a variety of other influences - gypsy music, for example, or jazz.
Klezmer does not have to have a tidy, clean sound like classical music. Some of the best klezmer tracks have a lot of things going on, with different instruments playing, sometimes the same melody, sometimes varying from each other. Think of the chaotic sound you get when a synagogue congregation sings together. You may prefer your klezmer more clean-cut with a very obvious accompaniment and a lucid lead instrument playing the tune. You should listen out for the telltale Jewish ornaments, though - the sobs, the wails and the chirrups created by the instruments.
A good arrangement means that the musicians have thought about the structure of the track. Listen out for whether the music starts quietly and then builds in a massive crescendo. Does the tension build up at the beginning and then does the intensity drop somewhere in the middle to be built up again at the end? There is no wrong or right way to do this - it just comes down to preference.
Some bands included in the competition play traditional dance tunes with an oompah bass line, a fiddle or accordion playing rhythm and a lead clarinet or violin playing the tune. Other bands may fuse klezmer with other music styles. The thing to remember here is that klezmer itself is not a pure musical form. From the outset, klezmer musicians have been open to outside influences, particularly Greek, Turkish and gypsy music. So fusions with other styles are perfectly legitimate in the context of klezmer idol.
Do not let sound quality put you off. This has a lot to do with budget rather than actual talent and the ability of the bands themselves. Some bands have managed to get record deals and have been able to have professional recordings made, other bands have gone out and paid for professional recordings themselves. Some bands have entered live recordings of gigs, together with warts and all. Go on, listen for yourself.
Laoise Davidson is head of information at the Institute of Jewish Music in London. She also plays fiddle in her own klezmer band, Ghetto Plotz.
Klezmer Idol is run jointly with the Jewish Music Institute. If you enjoy klezmer, find out more about this summer's KlezFest activities from August 12-17 in London (tel: 020 8909 2445 or see jmi.org.uk for details). Highlights include music and singing lessons with top international klezmer talent, plus the Ot Azoy! Yiddish crash course.