The research ”Laboratory and Field Studies on Infrasound and its Effects on Humans”—is a foundational paper by Swedish researcher Ulf Landström, published in the Journal of Low Frequency Noise and Vibration (Vol. 6, No. 1) in March 1987. It explores how infrasound (sounds below 20 Hz) impacts human perception and physiology, drawing from both controlled lab experiments and real-world field observations. This work has been cited in later studies on topics like fatigue, animal behavior, and even occupational health standards. I’ll break it down here, including the abstract, methods, key findings, reported effects, and conclusions, to give you a comprehensive overview. Note that while influential, this is from the late ’80s, so modern research has built on it with mixed results on infrasound’s health implications.

The Abstract in Full

The paper’s abstract sets the stage: ”In many working environments the total noise energy is dominated by infrasonic frequencies. Exposure to this type of low frequency noise has, by several authors, been correlated to different effects on human subjects. Recent laboratory experiments have thus indicated correlations between noise, perception and other effects on humans. Exposure to infrasound therefore appears to become a hygienic problem when the pressure level exceeds the threshold of perception. The present paper is a description of various laboratory experiments on perception and the physiological effects of infrasound. Subjects were exposed to pure tones and broad-band noise within the infrasonic range. Changes in perception, and physiological reactions, during different types of exposure are described. The paper also includes levels and frequency analyses of noise emanating from some of the most common infrasonic sources: buses, lorries, trains, railbuses, ships, helicopters, manoeuvre rooms and mills. The characteristics of the noise spectra are compared and related to the threshold of perception. Finally, field studies on physiological changes correlated to wakefulness in typical and authentic infrasonic noise environments are described.”

In essence, Landström argues that infrasound becomes a workplace health issue only when it’s perceptible, linking it to various effects while emphasizing the role of perception thresholds.

Methods: How the Research Was Conducted

Landström combined lab-based experiments with field measurements to provide a balanced view. Here’s the breakdown:

• Laboratory Setup: Tests occurred in a specialized pressure chamber (2.0 m x 1.6 m x 1.2 m) equipped with eight 50 W loudspeakers and two 100 W amplifiers to generate clean infrasound with minimal harmonics (first harmonics over 40 dB below the fundamental frequency). Background noise was kept low at 50-55 dB(lin) or below 50 dB(A). This setup acted like a Helmholtz resonator for precise control.

  • Participants: Included 10 deaf and 10 hearing subjects in some tests to compare sensory responses.
  • Exposures: Subjects faced pure tones (e.g., 6 Hz at 95-115 dB(lin) for 20 minutes; 16 Hz at 80-100 dB(lin)) and broad-band noise in the 2-20 Hz range. Some exposures were 10 dB above or below individual hearing thresholds. Additional comparisons involved low-frequency noise (42 Hz at 70 dB) vs. high-frequency (1000 Hz at 30 dB), and even EEG-regulated noise to check for brainwave synergies.
  • Measurements: Hearing and vibrotactile (body vibration) thresholds were assessed using sinusoidal frequencies. Physiological responses were tracked via EEG (brain waves) for wakefulness and EKG (heart activity). Exposure durations ranged from 20-30 minutes.

• Field Studies: Landström analyzed real-world infrasound sources like vehicles (buses, lorries, trains, ships, helicopters) and industrial sites (manoeuvre rooms, mills). He measured noise spectra and levels, comparing them to perception thresholds.

  • Exposures: In authentic environments (e.g., dumpers, helicopters, railway engines), participants experienced 30-minute sessions of noise alone, vibration alone, or combined stimuli, mimicking occupational conditions.
  • Focus: Emphasis on wakefulness changes in these settings, with annoyance ratings collected.

This dual approach allowed Landström to bridge controlled science with practical applications, referencing earlier works like Johnson (1980) on thresholds and Leventhall (1980) on effects.

Key Findings: What the Data Revealed

The study uncovered nuanced insights into infrasound’s detectability and impacts:

• Perception Thresholds: For pure tones, hearing thresholds were around 110 dB(lin) at 4 Hz, dropping to 90 dB(lin) at 20 Hz. Broad-band noise was detectable 1-5 dB lower. Vibrotactile sensations kicked in about 20 dB above hearing thresholds, with no difference between deaf and hearing people—suggesting it’s a body-wide response, not just auditory.
• Wakefulness and Drowsiness: Exposure above thresholds (e.g., 115 dB(lin) at 6 Hz or 100 dB(lin) at 16 Hz) reduced wakefulness in hearing subjects, as seen in EEG changes, but not in deaf ones. This points to the cochlea (inner ear) as the key mediator. Below thresholds (e.g., 95 dB(lin) at 6 Hz), no effects were observed.
• Frequency Comparisons: Low-frequency noise (42 Hz at 70 dB) promoted drowsiness, while high-frequency (1000 Hz at 30 dB) increased alertness. No strong synergy was found between infrasound and individual EEG frequencies.
• Real-World Sources: Noise from vehicles and mills often neared or exceeded perception thresholds, with combined noise-vibration exposures causing the most drowsiness and annoyance.
• Overall: Effects like reduced wakefulness were tied directly to perceiving the sound, aligning with prior theories but emphasizing no harm below audible levels.

Reported Effects on Humans

Landström’s work highlights a range of potential effects, but stresses they’re perception-dependent:

• Physiological: Reduced wakefulness and increased drowsiness (via EEG); potential links to fatigue in occupational settings. In field tests, combined infrasound and vibration led to higher annoyance and lower alertness.
• Perceptual and Psychological: Annoyance, body vibrations, and sensations like pressure. The paper notes correlations (from cited studies) to breathlessness, panic, anxiety, and even wakefulness disruptions—but Landström’s experiments focused more on drowsiness than acute panic.
• No Effects Below Threshold: Crucially, no physiological changes occurred when infrasound was sub-perceptible, countering some broader claims about ”silent” effects.
• Vulnerable Groups: Hearing individuals were more affected than deaf ones, underscoring the auditory pathway’s role.

Exposure levels mentioned include 80-115 dB(lin) at frequencies like 4-20 Hz, with durations up to 30 minutes in tests (or 2 hours daily in related contexts).

Conclusions and Lasting Impact

Landström concludes that infrasound poses hygienic risks in workplaces only when levels exceed perception thresholds, as that’s when annoyance, reduced wakefulness, and other effects emerge. He recommends larger studies on synergies (e.g., with vibrations) and highlights common sources like vehicles as potential concerns for workers. Overall, the paper supports the idea that effects are mediated by cochlear stimulation, not mysterious ”inaudible” mechanisms.

This research has influenced guidelines on low-frequency noise, though later reviews (e.g., by the WHO) have debated ”wind turbine syndrome” links, often finding psychological factors play a role too. If you’d like me to pull up related modern studies or compare it to ocean/forest/wind turbine contexts from our earlier chats, just say the word!

Imagine the vast Atlantic Ocean as a grand orchestra, where the deep bass rumbles of schooling tuna blend with the high-pitched clicks of hunting orcas. For millions of years, this underwater symphony has guided migrations, hunts, and family bonds. But in the last decade, a new instrument has joined the ensemble: the relentless hum of offshore wind farms. These towering turbines, hailed as green saviors against climate change, emit low-frequency drones that could be muting the ocean’s natural chorus. And on the U.S. East Coast, a heartbreaking timeline of beached whales suggests our ”progress” might be hitting a sour note. Could these majestic creatures be sending a desperate SOS? Let’s dive into the frequencies at play—and why we might need to retune our turbines before the music stops.

The Tuna’s Low-Key Rhythm: Communication and Hunting in the Depths

Bluefin tuna, the silver rockets of the sea and a primary prey for Iberian orcas off Portugal, aren’t known for elaborate songs like whales. Instead, they rely on subtle acoustic cues to coordinate massive schools and ambush prey. These fast-swimming giants produce and detect sounds in the low-frequency range, where the ocean’s ambient hum is already thick with shipping noise.

Research shows that tuna generate pulses during feeding frenzies or struggles, often between 20 and 130 Hz—deep, throbbing vibrations that signal danger, opportunity, or group cohesion. Their hearing peaks even higher, around 400-500 Hz, with sensitivity dropping sharply beyond 800 Hz, allowing them to pick up on the grunts and thumps of nearby fish or predators. In a quiet sea, these signals travel for kilometers, helping tuna maintain tight formations during their annual migrations through the Strait of Gibraltar. But introduce human noise, and the signal gets lost in the static. Boat engines alone can mask these calls, scattering schools and turning a coordinated hunt into chaos.

For orcas shadowing these tuna runs, disrupted prey communication means harder foraging. It’s like trying to eavesdrop on a conversation in a crowded subway—vital intel drowned out before it reaches you.

Orcas’ High-Wire Act: Echolocation and Calls in a Noisy World

Killer whales, or orcas, are the ocean’s acoustic virtuosos. They use a repertoire of clicks, whistles, and pulsed calls for everything from pinpointing a tuna’s location to coordinating pod hunts or simply saying ”hello” across miles of water. Their echolocation clicks—the sonar pings that map the seafloor and spot elusive prey—span 10 to 110 kHz, with peak sensitivity between 15 and 42 kHz. That’s ultrasonic territory for humans, far above our hearing but crystal clear to these black-and-white maestros.

Communication calls dip lower, from 0.5 to 30 kHz, allowing pods to ”chat” during travels. In the wild, this toolkit lets orcas like the endangered Iberian subpopulation off Portugal execute balletic tuna takedowns. But vessel noise, peaking in the 100-1,000 Hz range, bleeds into their lower calls, creating an auditory fog that stresses mothers and calves alike. Echolocation fares better at higher frequencies, but cumulative noise from shipping and construction can still overwhelm, leading to fatigue, misfires in hunts, and even those bizarre sailboat ”attacks” since 2020—perhaps a frustrated echo of disrupted lives.

The Turbine’s Persistent Drone: Frequencies from Portugal’s WindFloat Atlantic

Enter the floating offshore wind farms, like Portugal’s pioneering WindFloat Atlantic, operational since 2020 off Viana do Castelo. This 25 MW array of semi-submersible turbines was a breakthrough for deep-water renewables, generating clean power for 20,000 homes without the seabed-pounding foundations of fixed farms. But beneath the waves, its soundtrack is less harmonious.

Operational noise from floating turbines like these centers on low frequencies below 200 Hz—a continuous hum from blades and generators, often peaking around 198 Hz. Levels can hit 145-149 dB re 1 µPa at the source, fading to 100 dB over 60+ km in calm conditions. Mooring lines add sporadic snaps up to 48 kHz, overlapping orca whistles.

This low-end rumble directly clashes with tuna’s 20-500 Hz world, potentially masking schooling signals and scattering prey just as orcas arrive for dinner. For orcas, it’s more indirect: the hum blends into shipping noise, but in tuna-rich corridors, it could amplify stress, forcing pods into riskier nearshore foraging. Studies on Scottish floating farms (Hywind and Kincardine) show no mass displacements yet, but long-term data is thin—especially for vulnerable groups like Iberian orcas. As Portugal eyes 10 GW more by 2030, the chorus of turbines could turn migration routes into echo chambers of confusion.

East Coast Whales: A Timeline of Strandings and Spinning Blades

Across the Atlantic, the U.S. East Coast tells a tale of temporal tragedy. Since January 2016, an Unusual Mortality Event (UME) has claimed over 200 humpback whales from Maine to Florida, with necropsies revealing propeller scars and fishing gear entanglements as culprits. North Atlantic right whales joined the crisis in 2017, with 17 deaths that year alone—mostly from vessel strikes. By 2025, the humpback UME lingers, with 28 strandings in Rhode Island and Massachusetts in 2024 alone.

Now, overlay the offshore wind timeline: America’s first farm, Block Island (30 MW, Rhode Island), went live in December 2016—months after the humpback UME began. Coastal Virginia’s 12 MW pilot followed in 2020, amid rising deaths. South Fork Wind (132 MW, New York) hit full operations in 2024, as Vineyard Wind began delivering power off Massachusetts. By March 2025, U.S. capacity reached 174 MW, with 43 GW in the pipeline.

| Year | Key Whale Events | Offshore Wind Milestones |

|——|——————|————————–|

| 2016 | Humpback UME starts (Jan); ~20 deaths | Block Island operational (Dec, 30 MW) |

| 2017 | Right whale UME begins; 17 deaths | Planning ramps up; no new ops |

| 2018-2019 | Humpback deaths peak (~50/year) | Leases awarded; construction delays |

| 2020 | CVOW pilot online; COVID slows strandings | CVOW operational (12 MW) |

| 2021-2023 | ~100 total humpback deaths; right whale crisis | Vineyard/South Fork construction; 5 projects cancelled amid costs |

| 2024-2025 | 28 RI/MA strandings (2024); UMEs ongoing | South Fork full ops (132 MW); Vineyard delivering; total 174 MW |

Coincidence? NOAA attributes deaths to booming whale populations meeting denser ship traffic (up 27% since 2019) and gear entanglements, not wind surveys. Yet the overlap is uncanny: strandings surged as turbines spun up, and construction noise (up to 250 dB at 10-1,000 Hz) echoes tuna-disrupting lows. Could cumulative acoustic chaos—wind hum plus propellers—be pushing whales into harm’s way? It’s a correlation screaming for causation studies.

Retuning the Ocean: A Call for Quieter Waves

The sea’s big animals aren’t attacking boats out of spite or beaching themselves for attention—they’re adrift in a noise storm we’ve unleashed. Tuna schools fracture under 200 Hz drones, orcas strain to ”hear” amid the din, and East Coast whales wash up as turbines multiply. Offshore wind is vital for slashing emissions, but if we ignore the frequencies, we risk silencing the ocean’s soul.

The fix? Innovate. Shift turbine designs to higher frequencies above 1 kHz, where they skirt tuna senses and orca calls—perhaps via advanced blade coatings or active noise cancellation. Mandate real-time acoustic monitoring at farms like WindFloat Atlantic, and pause expansions in migration hotspots until we map safe soundscapes. Governments, from Lisbon to Washington, must fund cetacean-safe tech, just as we’ve quieted aircraft for birds.

The ocean’s orchestra is irreplaceable. Let’s listen to its pleas and compose a harmony where renewables and wildlife thrive. What frequency will you amplify? Share your thoughts below—our seas depend on it.

Sources and further reading:
NOAA Fisheries UME reports, Tethys Marine Energy Database, and acoustic studies from Frontiers in Marine Science.*

Based on reliable sources, here’s a quick summary of the key frequency ranges I pulled together for each element you mentioned (focusing on underwater sound production or sensitivity where applicable, as these are often discussed in the context of marine noise pollution affecting species like orcas). I used logarithmic scaling in mind for the diagram (e.g., from 10 Hz to 200 kHz) to show overlapping or distinct bands clearly.

Category	Frequency Range	Notes
Bluefin tuna (hearing sensitivity; vocalizations are minimal/rare)	100–800 Hz (most sensitive around 400–500 Hz)	Tuna primarily detect low-to-mid frequencies; limited vocal output around 100–500 Hz.
Orcas (vocalizations)	0.5–40 kHz	Communication calls and whistles fall in this band.
Orcas (echolocation)	15–40 kHz (up to 125 kHz hearing range)	High-frequency clicks for hunting/navigation.
Offshore wind farms (operational noise, including WindFloat Atlantic and floating parks generally)	<200 Hz (often peaking around 100–200 Hz, dominant <100 Hz)	Low-frequency tonal and broadband noise from turbine operation and moorings; varies with wind/rotor speed.
Container ship traffic (shipping noise)	20–1,000 Hz (dominant 50–500 Hz, up to 10 kHz broadband)	Propeller cavitation and engine noise; low-frequency dominant in busy shipping lanes.
Fishing vessel sonars (fish finders)	20–200 kHz (common: 50 kHz low, 200 kHz high)	Dual-frequency systems for depth and target resolution; higher for shallow/inshore.
Military sonars (naval)	0.1–10 kHz+ (low: 100–500 Hz; mid: 1–10 kHz; high: >10 kHz)	Varied by type (e.g., low for long-range detection, mid/high for accuracy); active systems can be intense.

Note: Overlaps between human-generated noise (e.g., shipping, wind farms) and orca vocalizations (0.5–40 kHz) or echolocation (15–40 kHz) may disrupt communication and navigation. Fishing and military sonars also overlap with orca echolocation frequencies, potentially causing disturbance.

🌊 Summary Table Orcas

Purpose	Sound Type	Frequency (kHz)	Notes
Communication	Calls, whistles, clicks	0.5–25	Used for identification and group cohesion
Echolocation	Click trains	20–120 (up to 160)	Builds a 3D “acoustic image”
Hunting	Clicks + coordinated calls	20–100	Adjusted for prey type and environment
Long-distance contact	Low-frequency calls	1–5	Travels several kilometers