Fix 'NameError: name 'audio_classifier' is not defined'

[2abet]

This will fix the "NameError: name 'audio_classifier' is not defined" currently experienced by lots of users.

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[2abet]

@schmidt-sebastian pls help with this pull request.

[kuaashish]

Hi @whhone,

Could you please review this PR? It primarily resolves issues #5990 and #5817.

Thank you!!