The idea is to have a µC output random noise in the 25K to 70Khz range since it's very likely there's spillover into the <20K range, we hook it in so that it only runs then the space is closed.
- MicroController with network
- Amplifier that does these frequencies well (normal audio have low performance at these frequencies)
- Some Indicator lights (power, network-ok, active)
- Power source.
- Random patterns work best. Unpredictable patterns.
- Get the state from the MQTT topic
- Have a 5 min delay on the activation
Similar commercial products:
- About Ultrasound speakers: https://www.diyaudio.com/forums/planars-and-exotics/212650-ultrasound-speaker-20khz.html