In my previous post, we explored the dual nature of low-frequency sounds (0.05–50 Hz) and infrasound—how ocean waves can lull us into tranquility while wind turbines might induce subtle stress, even if we can’t consciously hear them. Today, let’s venture into another natural wonder: the forest. Forests are alive with a symphony of sounds, many of which fall into this low-frequency spectrum, creating an auditory environment that’s profoundly calming for most people. Why do these woodland whispers feel so restorative compared to the mechanical hum of turbines? We’ll unpack the sources, science, and human responses, drawing parallels to our oceanic and industrial contrasts. If you’re a nature lover, this might just make your next hike even more mindful!

What Are Low-Frequency Sounds in Forests?

Forests produce a rich tapestry of low-frequency noises through biophony (animal sounds), geophony (earthly elements like wind and water), and even subtle infrasound. These vibrations, often below 20 Hz and up to 50 Hz, aren’t always ”heard” in the traditional sense but are felt as gentle pulses in the air or through the ground. Key sources include:

• Wind in the Trees: The rustling of leaves and branches generates broadband low-frequency noise, especially in denser canopies. Wind speeds of 5-10 m/s can create infrasound around 0.5-10 Hz, similar to ocean waves but more modulated by foliage.
• Animal Calls and Movements: Low-frequency components from owl hoots (down to 10 Hz), frog choruses, or elephant-like rumbles in tropical forests (if we’re thinking broadly). Even insect wings or distant mammal communications add to the mix.
• Water and Weather Elements: Stream gurgles, distant thunder (infrasound from lightning can dip to 0.05 Hz), or falling rain create rumbling lows that propagate through the forest floor.
• Human-Made Intrusions: Occasionally, low-frequency noise from nearby roads or logging equipment, but we’ll focus on the natural side here.

Unlike the steady drone of a turbine, forest sounds are irregular and layered, creating a dynamic soundscape that’s evolutionarily familiar—think of it as nature’s white noise, but with a green twist.

How Humans Perceive These Sounds

Our bodies are remarkably sensitive to low-frequency forest sounds. While infrasound below 20 Hz doesn’t register in the inner ear like higher pitches, it’s detected via the vestibular system (balance organs), skin vibrations, and even the lungs’ resonance around 5-10 Hz. This can lead to subconscious effects: a slight lowering of heart rate, reduced cortisol (stress hormone) levels, and enhanced alpha brain waves (8-12 Hz), much like the ocean’s influence.

Studies show that exposure to forest soundscapes—rich in low frequencies—improves mood, attention, and cognitive function. For instance, ”forest bathing” (shinrin-yoku in Japanese) research demonstrates that just 20-30 minutes in a woodland setting, listening to these sounds, can boost natural killer (NK) cells for immune health and alleviate anxiety. The low-frequency elements play a key role: they mask urban noise intrusions and promote a sense of enclosure and safety, triggering biophilia—our innate affinity for nature.

However, perception varies. In dense forests, the ”sound attenuation” (how sounds fade) creates a muffled, low-pass filter effect, emphasizing bass tones and reducing high-frequency distractions. This can feel enveloping and meditative. Contrast this with infrasound from storms: it might induce awe or mild unease, similar to how turbine hums stress some people, but the organic variability often tips it toward calm.

The Calming Effects: Why Forests Heal

Forests stand out as a low-frequency haven for relaxation. Here’s why they differ so positively from mechanical sources:

• Restorative Power: A study in Environmental Health and Preventive Medicine found that forest sounds, with their low-frequency dominance, reduce sympathetic nervous system activity (fight-or-flight) while enhancing parasympathetic (rest-and-digest) responses. Participants reported lower blood pressure and better sleep after exposure—effects amplified by the infrasonic ”hum” of wind-swayed trees.
• Brain and Body Sync: These sounds align with theta waves (4-8 Hz) for deep relaxation and creativity. Unlike the repetitive turbine pulse, which can feel intrusive and vigilance-inducing, forest lows are stochastic (randomly patterned), mimicking a safe, nurturing environment. Evolutionary psychology suggests this stems from ancestral forests providing shelter and resources.
• Therapeutic Applications: Sound therapy using recorded forest ambiences (e.g., apps like Calm or Noisli) leverages these frequencies for stress relief. One meta-analysis showed that natural low-frequency sounds outperform artificial white noise in reducing perceived stress by up to 30%.

Potential downsides? High-intensity infrasound from storms or wind gusts can cause temporary vertigo or nausea in sensitive individuals, but this is rare and short-lived compared to chronic turbine exposure.

(Table: Quick Comparison – For visual clarity, here’s a simple breakdown:

This highlights how context shapes experience—natural variability wins for calm.)

Contrasting with Ocean Waves and Wind Turbines

Tying back to our earlier discussion: Ocean waves and forest sounds both harness low frequencies for harmony, but forests add a biophilic layer—scents, visuals, and tactile elements amplify the auditory calm. Waves are more ”open” and repetitive, ideal for meditation, while forests feel intimate and immersive, great for grounding.

Wind turbines, however, represent anthrophony (human-made noise), often lacking the irregularity that makes natural sounds palatable. Research from the World Health Organization notes that while turbine infrasound levels are usually below annoyance thresholds (e.g., <40 dB), the psychological context—knowing it’s ”unnatural”—can heighten stress. Forests, conversely, score high on the ”pleasantness” scale in psychoacoustic studies, with low frequencies contributing to a 20-40% greater relaxation response than urban or industrial noises.

Final Thoughts: Embracing the Forest’s Low Hum

Low-frequency sounds in forests remind us of nature’s subtle power to heal, even through vibrations we barely ”hear.” They offer a counterpoint to the stresses of modern life, much like ocean waves, but with an earthy, protective vibe that turbines can’t replicate. Whether you’re hiking a pine grove or listening to a forest playlist, tune into those deep rumbles—they might just recharge your soul.

What low-frequency natural sounds resonate most with you? Drop a comment below, and if you’d like a deeper dive into another environment (like deserts or mountains), let me know!

Sources: Drawing from studies in Journal of Environmental Psychology, WHO noise guidelines, and acoustic research from sources like Acoustical Society of America. All info updated as of latest available data.

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.

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

Många av världens innovationer kommer från att ha studerat hur naturen löst liknade problem. Velcro, och fler exempel.
Här är en bra text från the guardian att utveckla fler lösningar:

https://www.theguardian.com/environment/2022/nov/23/velcro-bullet-trains-and-robotic-arms-nature-mother-of-invention-aoe?mc_cid=048508f264&mc_eid=dc81692d56

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