The beginning of twentieth century was a golden age of a player pianos and piano rolls in US. Up till the great depression in 1933 there were issued billions of piano rolls of classical, popular, folk and dance music. A significant part of these rolls were issued only for a usagege of various ethnic US groups of immigrants. Titled as "foreighn" rolls (QRS) they played an important role in socio-cultural life of ethnic communities of that time and made an influence to a formation of a popular music in US. Unfortunately these rolls were forgotten and left outside of academic/musicological discussions up to the present time because of music researchers' attention only to the piano rolls of world-famous pianists and composers. Though fragmented research has been done by some music historians and ethnomusicologists (Roehl, 1961; Greene, 1992; Berkman, 2006; Weill, 2011; Kučinskas, 2014), US ethnic piano rolls are still "terra incognito" for a larger society of researchers, collectioneers and sound recording engineers. Main historical, sociological, technological and musicological aspects will be discussed with a demonstration of rare and unique sound recordings made in last years during the research on US ethnic piano rolls.
