Ringtrichter Richtungshörer Horchgerät (RRH) 1:72

 Acoustic devices had been used for finding and monitoring the position of enemy aircraft and their flight direction since World War 1. Although radio detection and ranging (radar) was already massively used, the Luftwaffe and heavy anti-aircraft artillery control units were still using the RRH acoustic devices (which were developed in the 1930s) for early warning against the approaching enemy bomber streams until the end of the Second World War