From the Editor 

What’s the loudest thing near your house that nobody else seems bothered by? For a lot of our readers, the honest answer is a wind turbine. If you’ve ever stood in a field explaining to a resident why 40 dBA is technically compliant while they insist the swish swish is ruining their sleep, you know that “compliant” and “acceptable” are two very different words. That gap is where this issue’s wind turbine noise section lives.

We open with Roberto Merino Martinez arguing that our standard metrics are perceptually blind to what actually makes turbine noise annoying, and Goldwind’s Yang Bing follows with hard wind tunnel numbers, 6.4 dBA of reduction from combining vortex generators with serrated trailing edges. Read them together and ask whether that’s a win, given what Roberto just told you.

Then the standards fight starts. Lars Sommer Søndergaard and Sylvia Broneske are mid revision on IEC 61400 11, while Carlo Di Napoli and the AFRY team show the 2024 update to ISO 9613 2 can push predicted noise levels up by roughly 5 dB in real projects. Aercoustics tests a long assumed effect, temperature inversions, against long term field data and finds the relationship weaker than conventional wisdom suggests. Susanne Könecke and her Hannover colleagues hand the community an open, FAIR dataset built for exactly these questions.

Then we step back from the engineering. Eugene McKeown, writing with Eoin King and Denis O’Hora, asks what actually counts as an “acceptable” acoustic change in the pursuit of decarbonisation. A 40 dBA limit can sit close to daytime background levels in rural Ireland but dominate a night-time soundscape that drops below 25 dBA, and amplitude modulation, that rhythmic swish or thump, is consistently more annoying than steady noise at the same level. His piece asks acousticians to reckon with the fact that the communities hosting turbines are rarely the same communities receiving the electricity.

Eoin King then returns with Franck Bertagnolio to introduce RESONATE, IEA Wind TCP’s new international task treating engineering, perception, and policy as one problem instead of three conversations that never talk to each other.

We close the section by looking backward. Isaac Old revisits the NASA Large Wind Turbine Program, acoustical research from the mid 1970s through the early 1990s that predates nearly everything else in this issue. As infrasound concerns resurface in today’s debates, Isaac asks how much of that decades old research still holds up, and how much is being rediscovered.

From there we shift into departments. Jim Thompson offers field stories that will make you wince before you laugh, from the executive who didn’t see the chain across the test track to the vibration crew chasing data through a tropical storm thirty feet off the ground. Send us yours. Kylfa and Salomon explain ultrasound and infrasound for readers of all ages, and Stig’s reference cards revisit the physics of wind tones, a nice companion to this issue’s “ABCs of Acoustics.” Dr. Eric Ungar passed away this year, and the column you’re about to read is likely his last, on organ pipes, written with the clarity and wit that defined his work. We’re planning a longer tribute for a future issue, and if you have a memory of Eric worth sharing, we’d like to include it.

We save two pieces for the very end. Somewhere off the coast of Hawai’i, a monk seal is growling, groaning, and whooping in frequencies that overlap almost exactly with the noise humans make near it. Don’t just read this one. Listen to it. We’ve embedded audio of Kekoa and Hoʻailona’s vocal bouts directly in the piece, along with video of a wild seal vocalizing underwater. No spectrogram does that whoop justice.

We close on a warning shot. David Woolworth’s piece on data centers and low frequency and infrasound measurement makes clear that this industry is growing faster than most communities can prepare for, and A weighted criteria still aren’t up to describing what residents actually hear. Consider this our formal invitation: we want more voices on this topic in our next issue, case studies, regulatory gaps, community response data, whatever you’ve got.

Let us know what you think.

-Manish Manohare