During the First World War, acoustic locators were invented to detect aircraft. Let's see more options:
In 1880, a certain Professor Mayer invented large ears that do not hold hands. They rested on the shoulders of the wearer:
Topophone by Professor Mayer, 1880
And the fact that these "ears" are directed, made it possible to approximately determine the location of the noise source, its location. Well, simply because it is worth turning away from him - and nothing is heard.
Here. And, of course, as soon as aircraft buzzed in the sky, ear trumpets were immediately put into military service. Now they were called acoustic locators and were required just for the timely detection of enemy aircraft and determining the direction - where to expect it from. It's as simple as that. No radio or even more so laser ranging. Just a big bell and an ear to it.
One of the first experiments on this topic - someone Rev M. J. Bacon and volunteers helping him try to listen to a balloon flying, Great Britain, 1898:
Rev. M. J. Bacon's experiment.
Promotional video:
British soundlocker Mk 1, 1914-1918.
Mobile four-pipe locator of the First World War.
American two-arm system, Fort McNair Army College, 1921.
With such ears, naturally, you can feel wise, like an owl.
Sometimes, however, artificial big ears (especially if there are more than two of them) supply so much information that more than one brain is needed to comprehend it. At least two. A Czech four-tube radar from the 1920s was operated by two people:
Czech locator of the 1920s.
Portable acoustic locator of the First World War.
Japanese Emperor Hirohito inspects a combat auditory tube unit, 1930s.
The 1930s French locator consisted of four hexagonal crap, each containing 36 hexagonal horns. Served by three operators:
French acoustic locator of the 1930s.
British locators of the late 1930s:
Royal Engineers testing an acoustic locator, UK, 1938
British combat acoustic locator of the 1930s.
Super-fancy German locator RRH (Ringtrichterrichtungshoerer), this is already World War II:
American locator 1943.
And here are ours - an acoustic air defense locator in besieged Leningrad. Blind soldiers of the Red Army, who defended Leningrad, served in the crews of the "rumors". With the help of special machines, they "listened" to the night sky, warning the command of the raids of fascist bombers long before they appeared in the sky over the besieged city.
Acoustic locator in Leningrad. The Great Patriotic War.