Related Information for Jonsi Jónsi is a pseudonym of, at least, two Icelandic artists:1) Jón Þór Birgisson is the lead singer and guitarist for Sigur Rós and half of Jónsi & Alex, known for his soft falsetto voice . He released his solo debut album, Go, on April 6, 2010.Birgisson grew up in Iceland, raised by parents who weren't particularly musical; his early memories include playing The Beatles at double speed on his turntable and listening to and playing along with Iron Maiden records. You can hear him spe.. read more