when the escorts detect you on passive sonar, they will head in your direction and start to ping. Even if you hear the ping, it just means that they have detected you, not that they have found you. When they know where you are they will drop DCs, if the DCs are close, you know they have found you...
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At that time, it is time to try evasive maneuver, the best one being to go as deep as possible to try to evade or go below their active sonar cone.
Last night, I watched 3-4 IJN escorts searching for me in RFB 2.0 and it looked quite realistic. They would circle around listening on passive sonar, intermittently switching to active sonar. When they detected my boat, one escort would make a run right over my position and drop DCs. After they lost me, they also dropped DCs at the wrong spot.