Unfortunately node.js and therefore node-red is not the greatest tool for that. If your comfortable with python you could probably use something like pyAudioAnalysis and send the results to nodered over mqtt.
Otherwise you could go the machine learning approach which was begun to be discussed for a different use case in this thread.
There is some web audio stuff for javascript that could maybe do this but im not aware of any available nodered integration unfortunately.
All the solutions will involve you doing some coding and googling around github as im afraid there is no simple solution for this use case in nodered.
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