Inspiration for projects comes from many places, and after asking my kids to not be too loud, I realized that this was something of a meaningless request. Without some identifiable standard for an upper decibel limit, it’s all kind of a matter of opinion. What I needed was something akin to an industrial stack light that would progressively light up like an audio VU meter, then blink a warning if things got too noisy.
What I came up with was the “Hello Light,” named by my son to signify the fact that you say hello to it and it lights up. It uses an Arduino Nano along with an electret microphone stuffed into a wooden enclosure near the bottom of the assembly to measure ambient noise, then signals strips of RGBW lights to progressively light up depending on sounds levels. In alarm mode, if the sound level exceeds a certain threshold, it flashes blue and red to signify things are too loud.
As it turns out, my kids have decided that it’s a fun game to see if they can trip the alarm function, so as far as keeping things quiet, it’s perhaps not the most useful device — though a lot of fun. Besides sound measurement, there are modes for a pulsing white light (taking advantage of the ‘W’ component of these strips) and a random color mode that makes a beautiful display seen at the end of the video below. Code for the build can be found here.