The phenomenon known as the worldwide hum has intrigued many, including myself. A well-known resource is the Worldwide Hum Map, where Dr. MacPherson discusses the hum extensively. In a YouTube interview, he suggests that the hum may be a result of individuals hearing internal sounds rather than an external noise. While I respect his extensive work and contributions to this topic, I have some reservations about this conclusion.
Dr. MacPherson notes that people report hearing slightly different sounds, which he interprets as evidence that the hum is internally generated. However, if you were to ask thousands of people to identify a specific frequency using a tool like the Online Tone Generator, many might struggle due to varying degrees of tone perception. This margin of error doesn't necessarily confirm that the hum is a subjective experience; it could also indicate that the noise varies globally.
Numerous researchers and enthusiasts have delved into this topic, yet the source of the hum remains elusive. An insightful video discusses general theories and touches upon gas pipelines as a potential cause. Another compelling video strongly suggests that gas pipes may be contributing to the hum, offering in-depth research and analysis.
Several years ago, I began to notice the infamous hum. It was subtle during the day due to environmental noise but became prominent at night when I lay in bed. Typically, it would start in the early hours of the morning and persist for several hours. This pattern continued for some time.
I observed that each cycle of the hum lasted about 15 to 18 seconds, although the low volume made it challenging to measure precisely. There seemed to be a cycle of approximately 22 seconds. The tone didn't fluctuate in pitch; instead, it started too quietly to hear, grew louder over a couple of seconds, and then faded away. This would continue for at least two hours each night. Initially, I attributed it to external factors like car engines, especially during colder nights, but the consistency made me reconsider.
A few years later, the hum became a constant presence whenever I was in a quiet environment, such as when going to bed. Living in the countryside near farms, I considered the possibility of machinery or diesel generators running at night. However, engines typically exhibit variations in sound due to mechanical activity, which wasn't the case here.
An interesting event occurred when the hum suddenly stopped one night, coinciding with the onset of warmer summer weather. It returned when the temperatures dropped again. Over the past couple of years, I've paid closer attention, trying to correlate the hum with weather conditions or seasonal changes, but it has since become a consistent tone regardless of these factors. Iit is plausible that the hundreds of extra homes which have been built over the years in our town could be a contributing factor.
I questioned whether the sound was a figment of my imagination. To test this, I attempted to record the hum using my mobile phone. Remarkably, the device captured the sound, although it was inaudible during playback. I consulted a friend who is an audio engineer. After analyzing the file, he noted:
"If someone presented this to me and asked if it was created by natural causes, I would say 100% no. Most of it is white noise; however, the low end is interesting. It's far too man-made to be natural. It rises from approximately 24 Hz up to 48 Hz and does it every 25 seconds."
This analysis aligned with my observations of the frequency and volume fluctuations. It's possible that the frequency shifts caused the hum to move in and out of my hearing range, creating the perception of varying volume. This experience suggests that the tone is real and not merely a product of my imagination.
Some theories propose that the hum could be related to medical conditions or medications. For instance, certain over-the-counter medicines like ibuprofen have been suggested as potential causes, though there's no conclusive evidence to support this link. While medical conditions like tinnitus or auditory hallucinations can cause individuals to hear sounds that aren't present, these typically don't align with the specific characteristics of the hum I've experienced.
It's also worth noting that some people report hearing a pulsating hum. I believe that the hum is a continuous tone and that the perceived pulsation may result from one's heartbeat and blood flow, especially when lying down at night. As a child, I recall hearing sounds like someone walking on gravel and occasionally hearing my heartbeat in my ears. When this natural internal sound mixes with the external hum, it might create the sensation of a pulsating noise.
One plausible explanation for the hum is the low-frequency sounds generated by underground gas pipelines. Turbulence within these pipelines can create pressure fluctuations that manifest as low-frequency sound waves or hums.
Gas pipelines are an integral part of modern infrastructure, transporting natural gas over vast distances. The movement of gas through these pipes can generate low-frequency sounds due to several factors related to the physical characteristics of the pipelines:
All these factors combine to create a complex acoustic environment where low-frequency sounds can be generated and propagated. The specific characteristics of the hum can vary depending on the local pipeline infrastructure, including differences in pipe sizes, materials, operating pressures, and flow rates. This variability could explain why people in different parts of the world report hearing hums with slightly different frequencies or patterns.
The Earth-ionosphere cavity acts as a resonant chamber for electromagnetic waves, leading to phenomena known as Schumann Resonances. These are global electromagnetic resonances excited by lightning discharges in the cavity formed by the Earth's surface and the ionosphere. The fundamental Schumann Resonance occurs at approximately 7.83 Hz, with higher harmonics at 14 Hz, 20 Hz, 26 Hz, and so on.
While Schumann Resonances are in the extremely low-frequency (ELF) range and primarily electromagnetic rather than acoustic, some theories suggest that interactions between these electromagnetic fields and human physiology could contribute to the perception of the hum.
Microseisms are continuous, low-amplitude seismic waves generated by natural phenomena such as ocean waves interacting with the seafloor. These can produce vibrations in the Earth's crust at frequencies between 0.05 Hz and 1 Hz. Although these frequencies are below the threshold of human hearing, it's hypothesized that under certain conditions, they could contribute to the perception of low-frequency sounds.
Some researchers propose that atmospheric conditions, such as wind patterns interacting with terrain or ocean waves, could generate infrasonic sounds (below 20 Hz) that might be perceived as a hum under specific circumstances. These sounds can travel long distances due to minimal attenuation at low frequencies.
Heavy machinery, compressors, fans, and other industrial equipment can produce low-frequency noises. In some cases, these sounds can propagate through the ground or air over considerable distances, especially during nighttime when background noise levels are lower.
Electric power transmission systems can emit low-frequency electromagnetic fields. While these are not acoustic sounds, there is speculation that they might induce vibrations in nearby structures or equipment, leading to audible hums.
Substation Transformers: Small substation transformers can hum loudly and be a nuisance to residents living close by. This humming, often referred to as "mains hum," generally occurs at a higher frequency (typically 50 or 60 Hz) than the infamous worldwide hum, which tends to be at a lower frequency. The transformer hum is caused by magnetostriction in the transformer's core and can be particularly noticeable in quiet environments.
Household Appliances: Even common appliances like refrigerators and freezers can hum due to their compressors. While these sounds are usually confined within the home, they can contribute to the overall noise environment. It's important to rule out these factors when investigating the source of the hum.
Determining the exact cause of the hum is complicated due to several factors:
Many are eager to find ways to stop or mitigate the hum. Unfortunately, I haven't found a definitive solution. Ignoring it can be challenging, especially when trying to sleep. Over the years, I've lost countless hours of rest due to this persistent noise.
I've experimented with several methods to find relief:
The worldwide hum remains a mysterious and often frustrating phenomenon. While various theories exist, from environmental factors to internal physiological conditions, my personal experiences suggest that the hum is an external and real sound. Recording and analyzing the hum has reinforced this belief. Although coping strategies can provide temporary relief, a definitive explanation or solution has yet to be found.
In summary, the worldwide hum is a persistent low-frequency noise experienced by people globally. While some experts suggest it's a subjective experience or related to internal bodily sounds, personal accounts and audio analyses indicate it may be an external phenomenon. Potential causes include environmental factors like gas pipelines and electrical infrastructure, though no consensus has been reached. Coping mechanisms such as earplugs, noise-canceling headphones, and white noise machines can offer some relief, but the hum continues to be an enigmatic issue that affects the quality of life for those who hear it.
Whether you perceive the hum as an external reality or an internal sensation, it's undeniably a profound and challenging experience for millions worldwide. This persistent noise can disrupt sleep, affect mental well-being, and impact daily life. If you're among those who are affected, please know that you're not alone. Many others share your journey and are striving to find answers and relief. Never give up hope to continue seeking support, exploring coping strategies, and advocating for understanding. Together, we can work towards finding solace and solutions. Your resilience and determination are a source of inspiration for all who face this mysterious challenge.