Sonar is equipment on a ship or a submarine that uses sound to find things under the water. It sends out a sound — the famous 'ping' you hear in submarine films — and waits for the echo to come back.

Sonar Sonar（聲納）is equipment是裝在 on a ship or a submarine船艦或潛艇上的設備 that uses sound用聲音 to find things under the water來尋找水下的物體。It它 sends out a sound會發出聲音 — the famous 'ping' you hear in submarine films就是潛艇電影裡那個有名的「叮」聲 — and waits for the echo to come back然後等回聲傳回來。

From how long the echo takes and which direction it comes from, the machine works out where an object is, how far away, and often how big. That is called active sonar.

From how long the echo takes根據回聲花了多久 and which direction it comes from和從哪個方向傳來，the machine works out這台機器就能算出 where an object is物體在哪裡，how far away有多遠，and often how big通常還有多大。That這 is called叫做 active sonar主動聲納。

There is also passive sonar, where you send nothing at all and only listen, because sending a ping tells the enemy exactly where you are.

There is also還有 passive sonar被動聲納, where you send nothing at all and only listen完全不發送任何聲音、只是聆聽，because因為 sending a ping tells the enemy exactly where you are發出叮聲會讓敵人準確知道你在哪裡。

Sonar is not only for war: fishing boats use it to find fish, and ships use it to measure how deep the water is.

Sonar Sonar is not only for war不只用於軍事: fishing boats漁船 use it to find fish用它來找魚，and ships and ships use it to measure how deep the water is用它來測量水深。

Animals do the same trick — bats and dolphins — and people often call that natural sonar, though the proper word is echolocation.

Animals動物 do the same trick也會這一招 — bats and dolphins蝙蝠和海豚 — and people often call that natural sonar人們常把這叫做天然聲納, though the proper word is echolocation不過正確的詞是echolocation（回聲定位）。

The word also gets used loosely for noticing things: 'that never showed up on my sonar' means I never became aware of it, though for that meaning most people say radar instead.

The word這個字 also gets used loosely也會被鬆散地用 for noticing things來說「注意到」某件事: 'that never showed up on my sonar'「that never showed up on my sonar」 means意思是 I never became aware of it我從來沒有注意到它, though for that meaning不過對這個意思 most people say radar instead大多數人會用radar這個字。