Acoustic Location and Sound Mirrors

MusicThing pointed me to this awsome webpage about pre-radar methods of tracking ships and warplanes. The super high tech solution was essentially to just plug giant tubas into soldiers ears.

Acoustic Location and Sound Mirrors

Acoustic location was originally applied to determining the presence and position of ships in fog.

Acoustic location was used from mid-WW1 to the early years of WW2 for the passive detection of aircraft by picking up the noise of the engines. It was rendered obsolete before and during WW2 by the introduction of radar, which was far more effective.