drain noise & smell

the kitchen extention single story is nearly completed but now I have access to the kitchen I can hear from the main waste drain pipe going into the floor noise from the drain system. i.e. if someone uses the shower upstairs. however I also hear noise from the pipe if the next door neighbours turn on taps etc. the pipe is about 100 mm diameter (brown) at the moment there is no covering on it with only a single 40 mm pipe running into it. I know from watching the building going on the pipe runs about 3.5 meters towards a man hole which the builders had to put in. (the man hole is outside the extention.) the drain between the houses is shared. Main thing is how to get rid of sound and do I need to get the builders to change something add something etc. There does not seem to be smells coming from the pipe. I presume this is becuase the man hole is right by the main venting stack pipe thingie on the side of the house. Any help or suggestions.

Buy some cotton wool balls and stuff them in yer lugs.

Thanks but I want a long term solution not just a quick one. And no I dont want to cut my ears off or anything. Anyone with a real solution please let me know.

PS last night it also started to smell.

Thanks