We've got a relatively new house, and since a year or so the water pipe close to the main valve makes a humming/singing noise for 1-2 seconds when a tap is opened or the washing machine lets in water.
Initially I just ignored it, as it's only brief, but recently I also heard a whistling noise in the ceiling briefly when the toilet was flushed. This has now gone, but the sound near the main valve is still there and I realised this probably isn't normal. Based on my Google search it's got something to do with water pressure.
Video of the sound here, my wife opens the tap twice (make sure you turn on the sound, by default imgur seems to disable it): https://imgur.com/QBx8ubl
Before I call a plumber, I'd like to get Geekzone's opinion what this is? Should I be worried?