Finally, we have a data set with construct validity and with significantly reduced confounding factors. Once we crossed the threshold of roughly 17 000 map entries, we then applied a very strict set of criteria to filter the raw information, resulting in just over 3000 high-quality entries to the database and World Hum Map. If you are experienced in statistical techniques, then feel free to download the database, and let me know what you learn.
One risk of applying stringent criteria for map inclusion is that there will be people who feel excluded, marginalized, or that we don’t believe them. Nothing could be further from the truth. One important result of our project is the realization that not only is the world awash in unwanted and nuisance low-frequency sound and infrasound but also that many of these sounds share many characteristics with the World Hum. In some cases, it can take considerable effort to separate the two and to track down exactly what is causing the disturbance in question. Here is your guide for doing that.
On this last day of 2019, I admit to a sense of disappointment that I cannot devote more time to this project. I am also grateful that we have Henrik, one of our resident scientists, and Jason Lewis, our volunteer programmer, who have both done heavy lifting to help bring the 3.0 Hum Map to fruition.
Slowly but surely we move toward the solution to this mystery. Just a few days ago, I chuckled out loud when, later at night, I heard that familiar distant idling engine noise and said to myself, “I wonder what that sound is?”. As long as I and others never lose that sense of scientific mystery and discovery, we will get to the bottom of it.