I work with audio, sometimes bird sounds (for interactive encyclopaedias), playing the driest, clearest, sound into the app is often right, but not always. You

I work with audio, sometimes bird sounds (for interactive encyclopaedias), playing the driest, clearest, sound into the app is often right, but not always. You make a good point about the microphones. Sweeping through a sinewave can broadly tell you something about what the phone mic 'hears'. Most city birdsong ambiences are very complex soundscapes. There's some important characteristics in the higher frequencies of birdsong that will not be 'heard'. GPS helps to narrow down the the potential bird choices. So over time apps will learn and become more accurate. The open source Spleeter technology, unmixing stereo music, and its ilk, may be helpful run in real time allowing the app to ignore sound that is not birdsong.