Talk:Type 93 Passive Sonar/@comment-10504253-20140908064039/@comment-112.198.64.83-20150207092218

Sonar in this case refers to active "ping" sonar while Hydrophones refer being the early passive sonar devices used to listen for echoes from sonar pings.

As Active Sonar was the best thing in ASW during the time period (ASDIC and all) and hydrophones are used in conjunction with it, it justifies Sonar having a larger value than hydrophones.