Sony ICD-PX470 Help Manual page 114

Note
While "Audio IN" is selected for "Ext. Input Setting" is in progress, the Recording Filter function does not work.
If one of the recording levels for music is selected for the sensitivity level of the built-in microphones, the recording filter "NCF(Noise Cut)" is turned
off because it is optimized for voice recording.
Hint
To cancel the Recording Filter function setup process, select "OFF" in step 2.
Related Topic
Selecting the audio input type and the sensitivity level of the external microphone (Ext. Input Setting)
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