Theory has made great progress during recent years in calculating the fundamental properties of monatomic hydrogen in crystalline silicon. By applying the DLTS and DDLTS method we use the hydrogen-carbon complex which consists of an electronically inactive carbon atom on a substitutional lattice site and a hydrogen atom near the bond-center position to detect theoretically predicted properties of hydrogen in silicon. The results of two independent experiments show that there exists a coupling of the electronic and structural properties of monatomic hydrogen, as predicted by theory.