info on Iban/Borneo Music

Hello Tuning Peeps,
Does any one have any info on the music of the Iban - an ex-headhunter
tribe of/in Borneo?
I heard one piece on the radio recently & was really taken with the use
of a plucked & hammered monochord in the piece & with the humming &growling
vocals that accompanied the monochord playing.
Currently I am looking for CDs of Iban music as well. Any suggestions
form knowledgeable ones?

zHANg