Ivan (Janez) Regen (known also as Johann Regen) (December 9, 1868 – July 27, 1947) was a Slovenian biologist, best known for his studies in the field of bioacoustics.Regen was born in the hamlet of Lajše (today part of Gorenja Vas, Slovenia) and became interested in insect sounds as a child. His family couldn't afford to pay for his schooling, so he studied first at the local seminary for which he received a scholarship, and slowly saved enough funds for the tuition fee in Vienna.