This is how it works in real life. In DW the sound model is simpler. It is not exactly known how much simpler. There are some layer effects, but quite weak. I played many test missions and was helped by others just to find there is any SSP effect at all. Just do some test, you'll see.
What I found: You get weaker signal if you are on oposite side of the layer. The loss of the signal strength is 10% to 50%. Very occasionaly you can loose narowband line, in some very specific distance I think it is possible to loose contact, but it never happened to me. Most often layer does NOT change your ability to track or even identify.
Surface noise has much stronger effects. Shallow listener is affected by it and his contacts will be masked by surface noise. The noise reaches depths about 50m with sea state=3 and your detection range is several times smaller. You can completely loose contact which you have identified with 4 lines just few feet deeper. This is also main reason why deep sonobuoy has bigger range.
Surface noise effect is gradully stronger towards the surface. On waterfall display you can see lines gradually 'sink' in the noise while getting shalow. Layer effects in DW give sharp intensity change, and they occur EXACTLY on the layer depth.
While testing, note that towed array is usually in different depth then ship. If possible, use Sphere array to test SSP effects. Also note that on american subs narowband display you can see line fading away if the target changes bearing. Target gradualy moves to next bearing 'beam'.
This can be mistaken as SSP effect is bearing change is slow.
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