Include a noise data collection widget in Decibels

1. What is the general goal of the feature?
This is to allow studies collecting noise data to do so using ODK
2. What are some example use cases for this feature?
There are many projects carrying out noise monitoring in cities across the globe
3. What can you contribute to making this feature a reality?
I have a team that will help in testing this from beta to the actual addition

This could be an interesting development - but wonder how accurate it would be.

Some studies suggest there's pretty variable accuracy depending on device type such as this study and this post on the CDC website. Both suggest that iPhones are more accurate than android devices - which makes sense given less standard hardware implementation on Android.

It seems that one important consideration would be that measurements taken on two different devices would not necessarily be comparable with each other - even if there was reliability within measurements taken on a single device.

I wonder what the real world applications of this might be, but I'd be concerned that the lack of inter-device agreement would make this too unreliable for a platform like ODK, which is meant to operate similarly across devices.

Yeah, this is true. Android doesn't give us enough information about the mic to calculate dB SPL accurately. We'd only be able to support a set of known devices that we have calibrations for (a lot of sound meter/dB apps do this) or add calibration to Collect itself. There's a good Stack Overflow post on the problems involved in calculating accurate dB here.

Another problem would be that the microphones on most phones/tablets is designed to work with voices and so can't measure amplitude after a certain level.

As much as I think Collect could support some devices and use cases, but it would most likely be a lot of effort to maintain device lists or add a calibration UI, and I'd worry that people would use it not realizing that they may not be getting valid data. I'd heavily recommend people look into using dedicated sound meter devices for carrying out these measurements.