An audiovisual installation mapping near-ultrasonic and ultrasonic phenomena in Tokyo. During my visits I often felt assaulted by the variety of high-frequency sounds—as a sound artist with heightened sensitivity to them, I was both suffering and curious. This work grew out of the city's dense web of human and animal deterrents. ![[installation.jpeg]] ## Mosquitos So-called ["Mosquitos"](https://en.wikipedia.org/wiki/The_Mosquito) have become quite popular in Japan. These high-frequency generators, designed to deter "loitering and rough sleeping", emit tones around 17–19 kHz—supposedly audible only to people under 25, though in practice much older listeners hear them too. Age-related hearing loss is called [presbycusis](https://en.wikipedia.org/wiki/Presbycusis) and varies greatly from person to person. Some Mosquito devices even offer an "ALL AGE" setting that lowers the frequency to reach a broader group by design. Originally developed by Compound Security Solutions (now Mosquito Loitering Solutions Ltd.), they were imported to Japan and used extensively in public spaces. But in the streets of Tokyo in 2026 I never saw the [Mosquito boxes I had found online](https://ja.wikipedia.org/wiki/モスキート_(音響機器)#/media/ファイル:Mosquito_Noise_Device.jpg)—the shift seems to be toward less conspicuous solutions, possibly from another manufacturer. When I could identify a source (not always trivial), I found only a couple of small holes or slits, most likely concealing powerful emitters. So in this short article, I will be calling all human deterrents "Mosquitos" even when they might be manufactured by other companies. ![[mosquito slits.jpeg]] _Mosquito "slits" in metal enclosures_ ![[mosquito holes.jpeg]] _Mosquito "holes" in the ceiling of a subway station_ Mosquitos are controversial and banned in some places (though, as far as I could establish, never nationwide). Because they target the young and sensitive by design, their use is discriminatory and problematic—especially for the very young, who may have their hearing damaged without realizing it. A study by the German Federal Institute for Occupational Safety and Health found they particularly affect infants and young children—who hear higher frequencies, cannot report their distress, and cannot remove themselves because accompanying adults often hear nothing. Reported effects include nausea, dizziness, pain, and disturbance of balance; the Institute could not exclude risks to health and safety. [The Council of Europe (2010)](https://statewatch.org/news/2010/july/council-of-europe-parliamentary-assembly-prohibiting-the-marketing-and-use-of-the-mosquito-youth-dispersal-device/) and the [UN Committee on the Rights of the Child (2016)](https://digitallibrary.un.org/record/835015?v=pdf) have both called for bans, citing children's rights to freedom of movement, peaceful assembly, and protection from degrading treatment. ![[mosquitone.png]] While researching this phenomenon, I came across a YouTube channel named [Mosquitone](https://www.youtube.com/@mosquitone-sounds). It supplies long videos of near-ultrasonic sounds designed to repel humans, such as [Mosquito sound｜Sounds that young people do not like│17.6kHz│6 hours](https://www.youtube.com/watch?v=3He0YPA-nEw). The comments are full of satisfied users who have deployed them against other people: _"The middle school-aged children in the new house across the street were making a lot of noise every night, chatting and playing ball with their friends in the street. I wanted to do something about it, and then I came across this video. I couldn't hear it at all, but when I started playing it at maximum volume, the children left within minutes. I was very impressed with its effectiveness, thank you."_ or _"There were some noisy college students in the store, so I tried playing this song, and they actually left. Thank you so much!"_ So not only is the city full of commercially deployed generators—regular people seem to enjoy using these frequencies to harm others as well. The only use of high frequencies I remember from my own childhood in Slovakia was setting high-frequency ringtones on our phones, so that teachers at school couldn't hear them. ## Setup For the recordings I built a scientific measurement setup around the [Gefell MK301E](https://www.microtechgefell.de/mikrofonkapsel?wl=477-MK301E#) capsule and its extraordinary frequency response (5 Hz – 100 kHz, ± 2 dB). I used it in two configurations: 1. Connected to the [ESI UGM 192](https://www.esi-audio.com/products/ugm192/) sound card (in 192 kHz mode) via custom audio adapters, Roga XLR-IEPE adapter and MM310 microphone body 2. Connected to the [Gefell MV240 USB](https://www.microtechgefell.de/datei/1118/MV-240-digital_d5YSB.pdf) microphone body that acts as a USB class-compliant soundcard. For most recordings, a custom iPhone app was used. Alongside reliable 192 kHz 24/32-bit recording it embedded metadata—precise time, date, location and gain—straight into the WAVE file (BWF and iXML) for future reference. This was crucial to the process, since I had to do many recordings quickly and didn't want to enter metadata every single time. ## Method The search for the (near)ultrasounds was intuitive, focused on areas with a strong incentive to prevent loitering. Akihabara, Shinjuku and Ginza were obvious candidates, confirmed by locals as having a high density of Mosquitos. During the research process I relied heavily on my ears and a live spectrogram to confirm the actual presence of high-frequency sounds. After some time, I began hearing "phantom" high-frequency sounds that turned out not to be there when I checked against the visual representation. I also recorded many "accidental" emissions in the wild, often of unknown origin—most likely AC units, fans and lighting fixtures. One of the presented recordings is of cicadas, whose calls reach far into the ultrasonic range, up to around 100 kHz. Ester Mládenková documented the recording situations (myself and the environment) on a phone camera, in video and stills, for future reference. ![[recording process.jpeg]] ## Presentation My custom-made app (based on Python and ffmpeg) processed the recordings into accurate video spectrograms, with either the original or slowed-down audio. Each video also displays its date and time (in my favorite [ISO 8601 format](https://en.wikipedia.org/wiki/ISO_8601)), equipment and location. My aim was to evoke surveillance footage—aesthetics pared down to pure function. ![[video export.jpeg]] The videos played on an old, repurposed Panasonic Toughbook; a second Toughbook showed the documentation of the recording process. Both were mounted in a customized military case, emulating the tools of a sonic-weapon researcher. The spectrogram audio came through a small horn speaker built for PA announcements, and an e-ink screen showed project information and a map of the recording locations. ![[Research of Tokyo's ultrasonics.jpeg]] ![[location map.jpeg]] ![[process documentation videos.jpeg]] Show as part of [[Artificial Ultrasonics Research]] exhibition. **Location:** ArtKIT, Maribor, Slovenia **Date:** `2026-06-04` → `2026-07-04`