Hydrophone performance on surface question

[Clacker]

Hi All,

Now that I've turned map updates off, I'm using the hydrphone to hunt.
Often I cut diesels and listen on the surface. I can hear contacts this way. Will performance be improved sub-surface as in RL and if so, does depth matter much?

Twice I've steamed into a destoyer net mistaking their sounds for merchants :-)

Thanks
Clacks