This is obligatory for construction sites in the UK, which is why most people wouldn't have heard one.<br><br>In general it's becoming a common alternative to the beeping sound.<br><br>It's actually safer with the white noise because the sound doesn't get drowned out by tools, machinery, etc., unlike a beeping sound.<br><br>Also noise pollution is a factor. The beeping sound can be heard up to 2 miles away. The white noise sound can be heard at a much lower volume.