These are a few recordings of a piano bass string using a AKG contact microphone (I think it was the 411a, not sure, to a MOTU 828 audio card.) We played the piano string with fingers, nails, beaters; sometimes with a vibrato or a slight glissando/portato. The recordings were made in Franche-Comté in 2006 for a composition by Joyce Beetuan Koh and PerMagnus Lindborg called "TreGraphie", for hyper-cymbal, voice, piano and computer. For more about the piece, check http://www.pmpm.tk, under compositions.
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here