As far as I understand it, they are directly pinging your sub if you can hear the noise.
They still may not be able to accurately locate you even if yhey ping you (because, for example, you may have passed through a thermal layer or the crew skill is low)
I think you wouldn't be able to hear the sound unless it directly hit the sub (or was very close) because it is emitted in quite a focussed beam so that submerged objects can be accurately tracked. However, don't take my word for that because I don't know much about it!
Might be best to wait for someone with a greater knowledge of these things!