This is not a Perl solution, but the command is taken from Speech::Recognition::Vosk. ffmpeg can easily record output from various inputs. Assuming that you have PulseAudio on your Debian system, this records from the Pulse device $device. 

ffmpeg -hide_banner -loglevel error -nostats -f pulse -i "$device" -t 
+30 -ac 1 -ar 44100 -f s16le "$output_file"

[download]

Which device is the correct one, you can find using the following pactl command:

pactl list short sources

[download]

In reply to Re: Diverting audio output to a file. by Corion
in thread Diverting audio output to a file. by phirun

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