As part of my work at MACH Acoustics – understanding how internal ambient noise levels affect different environments – I was inspired to create an indicator that shows when noise becomes higher than the base level. Some solutions already exist but they are pricey (because they used calibrated sound level meters), and not very engaging. I wanted something that could sit in a classroom and be a friendly indicator for the teachers and students, bringing the noise back down and perhaps learning something in the process!
The operation is best described by the video below and commented code. I’ve added a handy GUI that allows the user to do a number of things:
- View the mic reading, background sample, instantaneous sample, current colour and sample difference.
- Change the threshold between colours and benchmark colour.
- Set continuous sampling, direct LED/mic feedback
- Resample the background
- Set the frequency band that is used for the amplitude average – this is useful to demonstrate that it is working and also to ignore low frequency to only show speech for example; screechy children in a classroom!
Its only a prototype concept at the moment. I’d like to design an enclosure that would suit the particular environment, such as a glowing star or dragon for a classroom.