How to validate that an audio algorithm result is independent of microphone device?
There isn't a universal pre-processing chain, but here are some common ones that I'd look out for:
1) Noise Gating
If a signal is below a certain threshold, the mic is muted. To identify: You'll see a VERY quiet noise floor, followed by a sudden spike in level.
2) Automatic Gain Control (AGC)
Mic volume modulates based on the signal level. This will be difficult to identify unless you have multiple recordings from the same system, which will show modulation in the noise floor based on the signal level.
3) Compression
This one should be self-evident. You'll see a very steady signal level that makes the waveform look like a &quot;block&quot;, i.e. not much changes in level throughout the entire recording.
These are all relatively simple real-time processing examples. There may also be more sophisticated post-processing applied in some cases, such as noise suppression.