The results of Novick (1958), Griffin (1962), Kay & Pickvance (1963), A. Pye (1966), Schnitzler (1967, 1968), Ajrapetjanz & Konstantinov (1967), and Konstantinov & Sokolov (1969) show that Rhinolophus ferrum-equinum Schreber, 1774 (RF) produces long pulses of constant frequency with a slight upward sweep at the start and a downward sweep at the end. These are similar to the sounds of Chilonycteris rubiginosa fusca J. A. Allen, 1911 (CR) described by Griffin & Novick (1955), Novick (1963a), Novick & Vaisnys (1964), A. Pye (1967), and Schnitzler (1970). Therefore it is interesting to compare the sound emission of both species in a similar orientation situation, while flying from a starting place across a room to a landing bar. The flight distance was 6.5 m in RF and 2.4 m in CR. The experiments with RF were done at the Zoophysiologisches Institut in Tübingen and with CR at the Rockefeller University and the Institute for Research in Animal Behavior in New York.