Regen was born in the hamlet of Lajše in Trata (today part of Gorenja Vas, Slovenia)[1] 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.

[2] In the meantime Regen began his research in animal physiology, being one of the first Slovenian scientists to work abroad after the World War I.

[3] He also studied other physiological phenomena in insects, such as breathing, hibernation, the development of pigment under different conditions, and ecdysis.

[5] He was a private researcher since 1911, but remained in touch with Slovenia, supporting several local societies and cultural institutions, and establishing Slovene terminology for the fields he worked in.