Hydrolyzes the sphingolipid ceramide into sphingosine and free fatty acid at an optimal pH of 6.5-7.5. Acts as a key regulator of sphingolipid signaling metabolites by generating sphingosine at the cell surface (By similarity). an N-acylsphing-4-enine + H2O = a fatty acid + sphing-4-enine N-glycosylated. Belongs to the neutral ceramidase family.