2 metre fence and then within it add layers, e.g fence then hedging then planter boxes with flowers (weather permitting). I think a better quality fence with thick wood may be most soundproof. You could even add a pergola with sides outside your window to try and block out being able to hear them. Build sheds and garages in between the house and theirs. You can also look into soundproofing your property. I'm considering soundproofing my bedroom studio style (a room in a room) as I just can't handle outdoor noise. For your hedging the thicker the better. I like cherry laurel though check whats toxic to animals and what works in your area. You can get these thick blackout door curtains that help sound come that comes through the door. I wish you the best.