Ashley Schmidt no longer spends much time in her garden in North Garland, a suburb of Dallas. She has also given up cycling to the local parks where she used to take close-up photographs of bugs, lizards and toads.
The reason is the delivery drones passing overhead with her neighbours’ online orders. “They emit this very annoying buzz. It triggers my fight or flight response,” says the 44-year-old administrative assistant. “You can hear the drones on approach and you can hear them inside your home when they pass directly overhead and then you hear them as they leave.”
How many drones we are talking about
Delivery by drone was a novelty not long ago. It is now part of everyday life in parts of the United States. Amazon Prime Air is expanding to nearly 500 cities and towns, delivering items that fit in a space the size of a shoebox, and has launched to customers in and around Darlington in the north of England. Walmart runs its own service. Smaller operators are appearing too — in some US cities you can order flying treats from a local pizza place or ice cream parlour.
Why the noise annoys out of proportion
This is the genuinely interesting part, because the complaint is not simply about decibels.
While the steady passing of traffic blends into the background, the sudden whine of a drone’s rotors pierces the everyday hum. The sound is “particularly noticeable, even when overall sound levels are relatively low”, says Antonio Torija Martinez, professor in acoustic engineering and psychoacoustics at the University of Salford.
Unlike planes, drones operate at low altitudes and may fly directly over residential areas. “They can expose communities that have not previously experienced significant aircraft noise, and who may therefore be more sensitive to changes in their local soundscape,” he says.
He points to research showing that people respond strongly to a noise when they consider the source to be “novel, intrusive or frequent” — and notes that people who benefit from a drone delivery service may be less bothered by it. That is the uncomfortable core of the problem: the annoyance is distributed to everyone under the flight path, and the convenience is delivered to one doorstep.
He expects complaints to grow: “At the moment we are seeing some of these problems localised in some areas, but… as the drone sector expands, more and more of these complaints will happen.”
In the US, the Federal Aviation Administration regulates commercial drones and has come under fire for allowing noisy delivery operations. The FAA says operators and local community leaders have primary responsibility for addressing community concerns — which is to say the regulator has placed the problem with the company causing it and the neighbours living with it.
The engineering answers
London-based Greenjets set out to tackle both “noise level and the frequency of that noise”, as Darren James, the company’s future technologies lead, puts it. Standard drones use spinning propellers that slice through open air, creating the high-pitched buzz. Greenjets encloses the spinning blades inside a pod, muffling the sound and directing it away from the ground. It also uses slower rotor speeds and materials that reduce vibration noise. The company claims the system cuts drone noise by at least two thirds.
A second approach comes from Detroit. Greg Sharrow was trying to film a violinist from a difficult angle in 2012, and a drone was the only solution except that it would be far too noisy. “I knew that most of the noise from the drone was coming from the propeller, not the motor,” he says — specifically the blade tips, swiping through the air. So he asked what a tipless propeller would look like, and Sharrow Engineering now makes twisted propellers that reduce noise.
Who is actually buying
Not, mostly, the delivery companies. Greenjets’ low-noise technology has been used by police and harbour security teams in Germany, and has helped conservationists in Africa track poachers from above without being detected.
Battlefield drone operators have obvious reasons to stay quiet. “There are some efforts to reduce the sound of drones. The US Special Forces are interested, at an experimental stage,” says Robert Tollast, a research fellow at the Royal United Services Institute.
But he is clear about the priorities in the war between Russia and Ukraine, where speed beats stealth for larger drones: “Make it faster, not less quiet, seems to be the approach.” We have reported on that use at scale, including Ukrainian strikes on three of Yandex’s five data centres in a week.
So the commercial logic is the reverse of what the complaints suggest. A technology developed because suburban Texans are irritated finds its first serious customers among people whose requirement is not to be heard — and Amazon, which says it is working to reduce the noise of its fleet, has less pressure to pay for silence than a surveillance operator does.
Before it arrives here
Drone delivery is not operating at scale in Bangladesh, which makes this the rare case where the regulatory question can be settled before the problem exists rather than after.
The useful lesson from the American experience is that noise was treated as a detail to be managed later, and is now a political issue in hundreds of towns. Three things would be worth fixing in advance: a maximum noise level at ground level rather than at the aircraft, published route maps so residents know what will fly over them, and a named body that takes complaints — because the FAA’s answer, that this is for operators and community leaders to sort out, is what leaves someone like Schmidt with nowhere to go.
