Before I get to the main point, let me share some of the backstory. The three of us moved to a new house near a local street. Although the traffic volume is low, especially at night, we designed our house with noise considerations in mind, placing the acoustically sensitive rooms further from the street, with no windows of those rooms facing the street. The one furthest from any noise source was reserved for my 2 year old daughter. When winter almost arrived, my wife and I, began noticing a persistent buzzing sound throughout the house. It was difficult to pinpoint, and while we grew accustomed to other ambient noises, this loud hum - around 100Hz - became increasingly irritating. One night, while taking out the garbage, I finally identified the source. It sounded like a truck idling nearby, but without the truck in sight. Instead, I found it was a large air-source heat pump, hidden behind a fence covered with a reed mat, positioned directly in front of my daughter’s window. Our initial, very polite email to the neighbour, asking whether there is anything he could do to reduce the noise, was met with an unexpectedly rude response. He even suggested that mosquitoes from our property were noisier than his heat pump. With no willingness to cooperate, I had no choice but to involve my insurance company and lawyers. I also used a sound meter to measure the noise level at the fence line, recording over 54 dB(A) - far above the legal limit of 40 dB(A). The heat pump was so close, I could read the model number and fetch the specs, which confirmed my measurements. I also discovered that these heat pumps can be relocated up to 30 meters away with minimal effort, by extending the tubing, power lines, and refilling the refrigerant.
After a request from the other party to check the problem “on site”, I installed the fixed noise sensor and made it available on sensor.community, so that both parties of the potential lawsuit can get acquainted with the data. That way, I figured, if any modifications are made, we would have a point of reference to compare it to. I hoped this transparency might even help us avoid legal action. However there was no further communication from my neigbour, so we proceeded with the lawsuit. In the original complaint, we didn’t even mention the noise sensor, which started to continuously monitor the decibel levels, since we had enough data from the hand held sound meter and indoor recordings from the previous winter. With peak frequency spectrograms, we could clearly demonstrate that the heat pump operated throughout the night, pausing briefly for defrosting cycles.
I was amazed how well the sensor worked this winter. We were able to see instances when the heat pump worked with suboptimal performance, just by measuring the sound and temperature levels in front of it. We were able to share these findings with the court. Later, the neighbour inadvertently shared his power consumption data, which corroborated our findings.
Last week, we received the court dates by post. With warmer weather approaching, we finally felt like the torturous nights were behind us. One night, for the first time, the heat pump even turned off for a few hours, revealing the low background noise - contrary to my neighbour’s claims that the area was naturally noisy.
The next night things took an unexpected turn. After my daughter’s bedtime, we heard loud banging on the door. Our neighbour had called the police, accusing me of installing a microphone to eavesdrop on conversations on his property. When I went outside, the officers were already on my property, inspecting the sensor. The neighbour repeatedly insisted it was a microphone, and to the untrained eye, it did resemble one. I had to explain that it was a noise sensor and showed the officers the decibel charts. Although they seemed satisfied with the explanation, they warned me that unauthorized audio recording carries severe penalties. In Poland, for example, CCTV cameras cannot record sound. I assume similar laws exist in other EU countries.
The incident made me realize how easily misunderstandings like this can escalate. It was a case akin to swatting. Had the police taken my neighbour’s side, he could face prison time for disrupting a data gathering system. I could also face legal trouble if I misspoke - for instance, I wouldn’t recommend explaining how a noise sensor works to a layperson in these circumstances. This experience convinced me that we need clear signage or a widely recognized pictogram to identify noise sensors. A quick search revealed only icons for noise-triggered alarm systems. Perhaps someone could design a standardized sign for people to place next to their sensors, making them easily recognizable within the community.
I’m also curious about how professional noise sensors are handled. Do they include signage? How are they secured? I’ll probably learn more about this as my court case unfolds. In the meantime, I hope my story helps others navigate similar challenges. And despite everything, I still believe that sound sensors—and heat pumps, for that matter—are valuable technologies when used responsibly.