LärmLupe
Hardware / Web
27–29 October 2026
How loud is your street? A citizen noise sensor and a live map for Heilbronn.
Team Lead · 3D Design · Pitch
Green City Hackathon Heilbronn
- senseBox MCU
- Sound-level meter
- Blender
- 3D Printing
- openSenseMap
- Next.js
🎯 The idea
Official noise maps in Germany are calculated, not measured, and are updated only every five years. They show the big roads but miss the side street, the tram curve or the bar on the corner, and they say nothing about when it is loud. There was also no simple device yet that collects this sound data, so that is the problem our team focused on at the Green City Hackathon Heilbronn.
⭐ What we built
LärmBox: a small sensor for a facade, a tree or a backpack strap. A senseBox MCU reads a real sound-level meter 20 times per second, saves every second to the SD card and sends one-minute values to openSenseMap over WiFi.
Live map: laermlupe.de shows every box on a map with its latest minutes and hours, next to the WHO guideline values.
Privacy: only decibel values are stored. The box never records audio.
🧩 My part
3D design: I modelled the enclosure in Blender: six parts that print without supports, with a sealed lid, a rain hood with foam and a microphone pod that slides onto the main box.
Team lead: I split the work, planned what each of us would say at the fair and on stage, and talked to the mentors and the hardware desk to get the developers what they needed.
Pitch: I opened the final pitch with a live clap test. The room reached about 103 dB.
🏆 Result
25 teams took part. We reached the final five with the most fair votes and finished 4th in the final pitch. At the Open Space our boxes measured an average of about 65 dB(A), well above the WHO guideline of 53 dB for road traffic.
It was our first time working with hardware and 3D printers, and in three days we built a working product. Thanks to Arkadia, re:edu, aim and the Dieter Schwarz Stiftung for the hardware, the mentoring and the event.
💻 Tech
Hardware: senseBox MCU, DFRobot SEN0232 sound-level meter, OLED display, SD card
Enclosure: Blender, 3D printing
Data and web: openSenseMap, Next.js
👥 Team Heilbronner Lilienwind: Özgün Mert Şahin, Mehmet Taşkın, Eren Mutlu, Cahit Gerçekel