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Why Strange Hums Seem to Come From Everywhere

Deep sounds are difficult to localize, so a hum or rumble may seem to fill the sky even when it comes from distant machinery.

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On this page

  • How humans locate sound
  • Why bass frequencies confuse direction
  • Indoor resonance and distant sources
Preview for Why Strange Hums Seem to Come From Everywhere

Introduction

Low-frequency sounds are one reason that reports of mysterious “UFO noises” can feel especially convincing. A deep hum or rumble often seems to fill the entire environment rather than coming from one clear point. This is not because bass sounds have supernatural properties, but because the human auditory system is less precise at identifying their origin under many real-world conditions. When combined with night-time listening, distant machinery, atmospheric sound propagation or echoes from buildings, an ordinary source can seem to hover overhead or come from “everywhere at once”. Research in auditory science shows that these effects arise from the way the brain interprets timing, loudness and reflections rather than from any unique characteristic of unexplained aerial phenomena.[nih.gov]ncbi.nlm.nih.govNCBIBasics of Sound, the Ear, and HearingHearing Loss - NCBI Bookshelf…

Overview image for Low Frequency

How humans locate sound

The brain normally determines the direction of a sound by comparing what reaches each ear.

Two main cues are used:

  • Interaural time difference (ITD): the tiny difference in arrival time between the ears, measured in microseconds.
  • Interaural level difference (ILD): the difference in loudness caused by the head partially blocking sound before it reaches the far ear.

Together these cues allow people to identify the horizontal direction of many everyday sounds with remarkable accuracy. Additional clues come from the shape of the outer ear, head movements and echoes from the surrounding environment, which help distinguish whether a sound is above, below, in front or behind.[nih.gov]ncbi.nlm.nih.govNCBIBasics of Sound, the Ear, and HearingHearing Loss - NCBI Bookshelf…

Low Frequency illustration 1

Why bass frequencies confuse direction

Low-frequency sounds behave differently from higher-pitched sounds because their wavelengths are much longer.

The head casts little acoustic shadow

High-frequency sounds have relatively short wavelengths, so the head blocks part of the sound from reaching the far ear. This creates a noticeable loudness difference that the brain can use for localisation.

Deep bass waves, however, bend around the head much more easily. Both ears therefore receive almost the same sound level, leaving the brain with far less directional information.[NCBI]ncbi.nlm.nih.govNCBIBasics of Sound, the Ear, and HearingHearing Loss - NCBI Bookshelf…

Timing cues are useful but not perfect

For lower frequencies, the auditory system relies mainly on tiny differences in arrival time rather than loudness. This works well under controlled conditions, but it becomes less reliable when the sound is:

  • continuous rather than impulsive,
  • weak compared with background noise,
  • masked by echoes, or
  • dominated by a narrow band of low frequencies rather than a broad spectrum.

Modern hearing research shows that localisation depends on a combination of timing and level cues rather than a strict separation between low and high frequencies. Nevertheless, low-frequency sounds generally provide less precise directional information than sounds containing strong higher-frequency components.[PubMed Central (PMC)]pmc.ncbi.nlm.nih.govPubMed Central (PMC)Transaural experiments and a revised duplex theory for the localization of low-frequency tones - PMCFebruary 24, 2016…Published: February 24, 2016

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Why a distant hum can seem to fill the sky

Many sounds associated with reported “sky hums” originate from sources that are both distant and rich in low frequencies.

Examples include:

  • heavy industrial equipment,
  • electrical infrastructure,
  • large ventilation systems,
  • diesel engines,
  • ships or trains many kilometres away, and
  • aircraft heard from long distances.

As sound travels, higher frequencies are absorbed by the atmosphere more readily than lower ones. By the time the sound reaches a distant listener, much of the sharper, more directional content has disappeared, leaving mainly the low-frequency rumble. Without those higher-frequency cues, the brain struggles to determine where the sound began.[NCBI]ncbi.nlm.nih.govNCBIBasics of Sound, the Ear, and HearingHearing Loss - NCBI Bookshelf…

This is one reason people may describe a mysterious hum as surrounding them or coming from directly overhead even when the physical source is on the ground and several kilometres away.

Low Frequency illustration 2

Indoor resonance and reflected sound

Buildings can make localisation even more difficult.

Low-frequency waves readily excite resonances in:

  • walls,
  • floors,
  • ceilings,
  • window panes, and
  • large rooms.

Instead of hearing a single incoming wave, listeners receive a mixture of direct sound and multiple reflections arriving from different directions. Standing waves can also create “hot spots” where the bass seems unusually strong in one part of a room and much weaker a few steps away.

The result is that the sound appears detached from its true source. A distant industrial fan, for example, may seem to come from the ceiling, a corner of the room or nowhere identifiable at all because the room itself is vibrating in response to the incoming low-frequency energy. Research into indoor acoustics consistently shows that reflections and reverberation reduce localisation accuracy, particularly at low frequencies.[Institute of Acoustics]ioa.org.ukInstitute of AcousticsProceedings of the Institute of AcousticsLOW-FREQUENCY SOUND SOURCE LOCALIZATION ASMarch 26, 2026…Published: March 26, 2026

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Why mysterious hums are often reported at night

Night-time conditions can make these effects more noticeable without requiring an unusual source.

Several factors combine:

  • everyday background noise falls, making faint low-frequency sounds easier to notice;
  • temperature and wind profiles can alter how sound propagates over long distances;
  • visual reference points are reduced, making people more dependent on hearing; and
  • the absence of clear directional cues encourages the impression that the sound is widespread rather than localised.

These conditions do not create mysterious sounds by themselves, but they can make ordinary low-frequency sources seem unfamiliar and difficult to place.

Low Frequency illustration 3

What this means for reports of UFO noises

The fact that a humming sound seems to come from everywhere is not, by itself, evidence of an aerial or unexplained source.

Auditory research provides a well-supported explanation for why deep sounds are frequently mislocalised. Low-frequency energy supplies fewer reliable directional cues, travels efficiently over long distances, survives atmospheric filtering better than higher frequencies, and is easily altered by reflections from terrain and buildings. Under those circumstances, a listener may sincerely perceive a hum as filling the sky even when it originates from ordinary infrastructure beyond immediate view. This perceptual limitation helps explain why reports of unexplained humming are common in UFO accounts while remaining entirely consistent with established principles of acoustics and human hearing.[nih.gov]ncbi.nlm.nih.govNCBIBasics of Sound, the Ear, and HearingHearing Loss - NCBI Bookshelf…

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Amazon book picks

Further Reading

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Browse more on Amazon:An to the Psychology of Hearing booksSpatial Hearing: The Psychophysics of Human Sound LocalizationThe Universal Sense: How Hearing Shapes the Mind

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Endnotes

1. Source: ncbi.nlm.nih.gov
Title: NCBIBasics of Sound, the Ear, and Hearing
Link:https://www.ncbi.nlm.nih.gov/books/NBK207834/?report=reader

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Hearing Loss - NCBI Bookshelf...

2. Source: journals.physiology.org
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Physiology JournalsMechanisms of Sound Localization in Mammals | Physiological Reviews | American Physiological Society...

3. Source: pmc.ncbi.nlm.nih.gov
Title: Pub Med Central (PMC)Auditory localization: a comprehensive practical review
Link:https://pmc.ncbi.nlm.nih.gov/articles/PMC11267622/

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PubMed Central (PMC)Auditory localization: a comprehensive practical review - PMC...

4. Source: pmc.ncbi.nlm.nih.gov
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PubMed Central (PMC)Psychophysics and Neuronal Bases of Sound Localization in Humans - PMC...

5. Source: pmc.ncbi.nlm.nih.gov
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PubMed Central (PMC)Transaural experiments and a revised duplex theory for the localization of low-frequency tones - PMCFebruary 24, 2016...

Published: February 24, 2016

6. Source: pmc.ncbi.nlm.nih.gov
Link:https://pmc.ncbi.nlm.nih.gov/articles/PMC4271773/

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PubMed Central (PMC)An Overview of the Major Phenomena of the Localization of Sound Sources by Normal-Hearing, Hearing-Impaired, and Aide...

7. Source: ioa.org.uk
Link:https://www.ioa.org.uk/system/files/proceedings/aj_hill_moj_hawksford_low-frequency_sound_source_localization_as_a_function_of_closed_acoustic_spaces.pdf

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Institute of AcousticsProceedings of the Institute of AcousticsLOW-FREQUENCY SOUND SOURCE LOCALIZATION ASMarch 26, 2026...

Published: March 26, 2026

8. Source: pmc.ncbi.nlm.nih.gov
Link:https://pmc.ncbi.nlm.nih.gov/articles/PMC3928360/

9. Source: pmc.ncbi.nlm.nih.gov
Link:https://pmc.ncbi.nlm.nih.gov/articles/PMC2045670/

10. Source: pubmed.ncbi.nlm.nih.gov
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Additional References

14. Source: pubs.asha.org
Link:https://pubs.asha.org/doi/10.1044/2022_AJA-22-00006

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ASHA PublicationsSound Localization of Listeners With Normal Hearing, Impaired Hearing, Hearing Aids, Bone-Anchored Hearing Instruments...

15. Source: youtube.com
Title: Interaural time difference and how to find your phone instantly
Link:https://www.youtube.com/watch?v=CqB95rj_txI

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This collection of videos provides concrete context on psychoacoustics and auditory sound localization. They explain how human hearing re...

16. Source: acoust.org
Title: Yet a microphone, a spea
Link:https://acoust.org/posts/reading-the-room/

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Reading the room: a primer on acoustic SLAM — acoust.orgApril 22, 2026 — Essay April 22, 2026 · updated May 8, 2026 · 18 min read READING...

Published: April 22, 2026

17. Source: youtube.com
Title: Is YOUR SUBWOOFER facing the WRONG way? How we locate sounds explained!
Link:https://www.youtube.com/watch?v=Ug6wJj6-7XA

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How Sound Localization Works: Timing + Intensity Differences...

18. Source: nature.com
Link:https://www.nature.com/nature-index/topics/l4/infrasound-propagation-in-atmospheric-systems

19. Source: youtube.com
Title: How Sound Localization Works: Timing + Intensity Differences
Link:https://www.youtube.com/watch?v=Kzgom_RaxoI

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Interaural time difference and how to find your phone instantly...

20. Source: resource.isvr.soton.ac.uk
Link:https://resource.isvr.soton.ac.uk/FDAG/VAP/html/localisation.html

21. Source: researchgate.net
Link:https://www.researchgate.net/publication/286800677_Human_sensitivity_to_interaural_phase_difference_for_very_low_frequency_sound

22. Source: impact.ornl.gov
Title: evaluating the location capabilities of a regional infrasonic net
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Link:https://www.sciencedirect.com/science/article/abs/pii/S0378595598002056