These people could not take up arms. However, blind fighters were used as "listeners" on sound locators. These bulky constructions with tubes of various sizes allowed the detection of the distant hum of approaching enemy planes. The sound locator teams would rotate the device until the sound in the specialist's ears was of equal strength. The "listener" would detect the approaching enemy and immediately alert their comrades. The first "listeners" were recruited from regular military personnel, but their effectiveness was lacking. At the end of 1941, the command enlisted the help of the blind, who had not just excellent but unique hearing, for the defense of the city. From the three hundred blind people remaining in the city, twelve men were selected—physically strong and enduring enough to withstand hours of duty. "The tension caused a terrible ache in the temples, and the neck vertebrae seemed about to crack. It took incredible effort, concentration, and stamina to listen to the sky, where at any moment a suspicious sound could appear," described the daily life of a "listener" the writer and siege survivor Semyon Bytovoy. The blind defenders performed their task excellently. The city was still quiet, but the "listeners" were already reporting the impending danger. They could even identify the type and model of German planes, and sometimes even their approximate number. Among these special fighters, there were casualties. Averkiy Nikonov died at his post in February 1942, and Vasily Tsyplenkov, who was demobilized in the summer of the same year due to health reasons, soon died of dystrophy. The remaining blind "listeners" survived until the complete lifting of the Siege of Leningrad in January 1944.