noun
Japanese war tuba; pre-radar acoustic locator
Historical term for a large acoustic detection device used by the Imperial Japanese Army before radar. Often referred to in English as 'Japanese war tuba' due to its horn-like appearance.
九〇式大空中聴音機は、敵機のエンジン音を捉えるために使われた。
The Type 90 large airborne acoustic locator was used to capture the engine sounds of enemy aircraft.
戦前の日本では、九〇式大空中聴音機のような聴音機が防空に用いられた。
In prewar Japan, acoustic locators like the Type 90 large airborne acoustic locator were used for air defense.
General term for acoustic locator; 九〇式大空中聴音機 is a specific model used by the Imperial Japanese Army.
The term is a compound of 九〇式 (Type 90, indicating the year of adoption, 1930 in the Japanese imperial year), 大 (large), 空中 (airborne), and 聴音機 (acoustic locator). It is a technical military designation with no deeper etymological layers.