Odd sound from upstairs drainage

[mr rob]

Recently, and during gusts of wind it seems the shower cubical and sink drain makes an odd sound, what could be causing this - any hints for me to look for? Real basic knowledge here!
thanks

 

[ktuludays]

I'm gonna guess they both drain into the soil pipe and when it's windy you get a pressure differential causing the noise. My toilet water fluctuates slightly during strong winds

 

[big-all]

throw in a pint off water or half a litre to make sure the "U" bends are full

 

[Hugh Jaleak]

Air passing over the top of the vent stack causes a slight negative pressure, and draws air up and out of the stack, The Victorians utililised this, with the addition of a Low Level air intake at the boundary, to ventilate the house drainage system. The Low Level vents ceased to be fitted a long time ago, but the action of air passing over the stack still serves to ventilate the drainage system, in windy conditions the effect is greater and so it is likely the water levels of WC's and other appliance traps may be affected.