“There goes the neighborhood” isn’t a phrase to be thrown about lightly, but when they build a police station next door to your house, you know things are about to get noisy. Just how bad it’ll be is perhaps a bit subjective, with pleas for relief likely to fall on deaf ears unless you’ve got firm documentation like that provided by this automated noise detection system.

OK, let’s face it — even with objective proof there’s likely nothing that [Christopher Cooper] is going to do about the new crop of sirens going off in his neighborhood. Emergencies require a speedy response, after all, and sirens are perhaps just the price that we pay to live close to each other. That doesn’t mean there’s no reason to monitor the neighborhood noise, though, so [Christopher] got to work. The system uses an Arduino BLE Sense module to detect neighborhood noises and Edge Impulse to classify the sounds. An ESP32 does most of the heavy lifting, including running the UI on a nice little TFT touchscreen.

When a siren-like sound is detected, the sensor records the event and tries to classify the type of siren — fire, police, or ambulance. You can also manually classify sounds the system fails to understand, and export a summary of events to an SD card. If your neighborhood noise problems tend more to barking dogs or early-morning leaf blowers, no problem — you can easily train different models.

While we can’t say that this will help keep the peace in his neighborhood, we really like the way this one came out. We’ve seen the BLE Sense and Edge Impulse team up before, too, for everything from tuning a bike suspension to calming a nervous dog.

[Yannick], aka [Gigawipf] brings us this (mostly) musical delicacy: a 3D-printed siren that’s driven by a brushless quadcopter motor, and capable of playing (mostly) any music that you’ve got the MIDI score for. This is a fantastic quickie project for any of you out there with a busted quad, or even some spare parts, and a 3D printer. Despite the apparent level of difficulty, this would actually be a great quickie weekend build.

First stop is Thingiverse, for the Mini Air Raid Siren model. Start that printing and get to work on the electronics. For the MIDI-to-ESC (electronic speed controller) conversion, any Arduino with USB support (ATmega32u4 or ARM boards) will work. The important bit is that you can run the MIDI-USB library. All that remains is a MIDI-to-servo pulse conversion and lookup table. Here’s [Yannick]’s file, but we’re guessing that you’ll want to tune your own siren.

How well does it work? See the videos below. Short notes, as well as note-offs, tax the quad motor’s ability to stop the siren rotor immediately. There’s a nice portamento effect as it ramps up between notes as well. You’ll need to pick your repertoire accordingly.

We have a strange affinity for musical sirens, so we’ll readily admit that [Yannick] had us at the word “spinning”. This is an easy project, with a pretty cool result. As far as we know, there’s only one 3D-printed, MIDI-controlled siren in the world, but it shouldn’t be hard to scale the siren model up or down to make different registers and effects. So who’s up for an entire symphony of these things?