Ordinary glass has very low sound absorption properties. Laminated is better, heated likewise, but overall you are better served by stopping the sound getting to the windscreen in the first place.
I've found under bonnet sound proofing effective, I used 3 layers of "flash band", a tar based product used to seal gutters and roofs, on the underside of my series bonnet, fitted with a TDI engine.
This, coupled with a similar treatment on the engine side of the bulkhead, had made the cab into a loud, but civilised place. Conversations are possible at 60 without shouting.
When I get the Wright off road mat fitted, and a higher ratio transfer box, I think it will be quite good.
Sound proofing is cumulative, it all adds up.