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Oh no. I hear the hum.

I first noticed the hum many weeks ago. When I first became conscious of it, I gave it little thought. Though this area is very quiet, engine noises can carry a long way. When I heard it in the middle of the night, it became more puzzling, because I couldn’t think of any reason why a large diesel engine would be idling a mile or two away in the middle of the night. Now that I’m aware of it, I hear the hum almost every day — or night.

Before I had read about the hum, I had described it to a neighbor the same way many others have described it. It sounds like a large diesel engine idling — a train engine, for example — about a mile or more away. It does not change pitch or volume. The sound is either there or not there. Eventually I Googled for something like “low pitched rumbling sound” and discovered that it is called the hum. It has been reported all over the world. Here is a link to the Wikipedia article. If you Google for “the hum,” you’ll find many articles about it. It has been reported that only 2 percent of people can hear it. Why me? My hearing is pretty good, especially for someone my age. Also it’s usually very quiet here.

At first I dismissed the sound as a form of tinnitus, or as some sort of pneumatic phenomenon having to do with how the outside air flows around the roof of my house. But after a few weeks, I became increasingly confident that the sound is real. Then it dawned on me to see if I could measure the sound with a sound-measuring app on my iPhone.

I have not yet done enough measuring to feel highly confident of what I’m seeing in the “Decibel X” app. But so far I think the app is confirming what I hear. When I don’t hear the hum, the background noise level averages around 30 decibels, at the whisper level. When I do hear the hum, the noise level averages about 37 decibels. The background noise here always seems to be concentrated at frequencies below 90Hz. But if I had to guess at the frequency of the hum, I’d put it as around 50 Hz.

Assuming that the hum is real, I have no theory about what is causing it. But I’m now 99 percent convinced that it’s real.

Does anyone else hear the hum?


  1. MHK wrote:

    Hi David:
    My husband and I have heard this engine idling noise at night for the past 2-3 months. We are in the southern part of the county and live near the large manufacturing plant located here. The facility makes a lot of noise day and night, but this “new” noise is different.
    Our nearest neighbor is a “shade tree mechanic” and we wondered if he was working on a vehicle at night, but all is quiet and dark at his place when the noise occurs. My description is exactly like yours-an engine idling noise that is consistent in tone.

    Sunday, March 28, 2021 at 9:34 am | Permalink
  2. daltoni wrote:

    Hi, MHK: Yikes! I wish we could get to the bottom of this…

    Sunday, March 28, 2021 at 9:38 am | Permalink
  3. Tom wrote:

    For months, beginning last year I heard a sound that began much like an engine starting and then smoothing out as if idling. At first I attributed it to construction that was taking place near me. The sound persisted and I began to think that it might be located in the crawl space under my house where the furnace/AC was located. I went nuts trying to locate this sound, but it faded before I could ever get close to what I thought might be the location of the sounds origin. I heard this sound mostly in the early morning. I have high frequency hearing loss and am ultra sensitive to low frequency sounds. I hear far off thunder when my wife hears nothing and the sounds that I heard were in that register. I have now sold that house so my days of investigating are over, but I am truly mystified by what I heard over a period of many months.

    Monday, March 29, 2021 at 9:30 pm | Permalink
  4. Dan wrote:

    I hear if you get the vaccine and you go out of range of 5G, you start to lose signal. You do live in a rural area…

    Thursday, April 8, 2021 at 11:35 am | Permalink
  5. daltoni wrote:


    Thursday, April 8, 2021 at 11:40 am | Permalink

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