Google cancelled its Fusion Table feature, which drives the Hum Map. We are in the process of switching over to a “homebrew” solution with the help of Jason Lewis, our young and highly talented programmer.
We’ll be back online soon. And, thanks to Henrik’s keen eye, we are about to deploy a highly valid and reliable data set.
Glen
World Hum Map and Database Project 
I have heard the hum the last two nights living in New Plymouth New Zealand having heard it maybe 7 years ago while living in Auckland New Zealand
If you have heard “some hum” twice (essentially) in 7 years it is likely a real (identifiable) sound and NOT “The HUM” (internally-sourced) that plagues many here 24/7/365 for many many years.