Digital noise reduction and removal (after analysis)

[phillprice]

My microphone is very noisy. While I don't believe its causing problems with identification its certainly annoying when listening back.

I notice that sox can help do some noise reduction, if you have a sample with just noise in it. Guess what - I have many hours a day with just noise in it :)

https://unix.stackexchange.com/a/427343 is where I sourced the commands, although I've not automated them yet, and I think a backup file would be useful, just in case if you were to automate this.

https://soundcloud.com/phillprice/sets/tawny-owls?si=1f58816152ff4528970e13c486d484cb

Basic steps are

Install

sudo apt install sox libsox-fmt-*

Find a file that is birdless (from overnight / now) and copying it to home

cp ~/BirdSongs/October-2022/08-Saturday/2022-10-08-birdnet-14\:51\:20.wav ~

Make a noise profile (mine complained sox WARN wav: Premature EOF on .wav input file)

sox 2022-10-08-birdnet-14\:51\:20.wav -n noiseprof noise_profile_file

Grab a file to home to test it (TEST ON THE COPY)

cp ~/BirdSongs/Extracted/By_Date/2022-10-08/Tawny_Owl/Tawny_Owl-91-2022-10-08-birdnet-02:22:44.mp3 ~

Test the filter

sox Tawny_Owl/Tawny_Owl-91-2022-10-08-birdnet-02\:22\:44.mp3 Tawny_Owl/Tawny_Owl-91-2022-10-08-birdnet-02\:22\:44-filtered.mp3 noisered noise_profile_file 0.31

Tweak and repeat at will. PLEASE DON'T DO THIS ON ORIGINALS

[matthew73210]

Thats actually a pretty neat idea, this could probs be done on samples before anaylis? Every x minutes take an empty samble and use as a filter. @mcguirepr89 what do you think? Maybe have it as an option for noisy environments or ones where there's always interference.

[Vollpflock]

Does this still work for you? My Pi is stuck after reboot, had to go back. And btw, don't you struggle with low audio volume?

[phillprice]

Yes still working although the commmand is in from as it somehow gets frequently forgotten and the noise returns. Sound seems to be fine enough to detect birds.

[peflo]

Still working for me as well - the only problem I have is that the live audio stream generally doesn't play for me now, but detection works just fine and recordings have the noise-cancellation enabled and play properly. No issues with volume.

[harrymnel]

My microphone gain also dropped and I can barely hear it. How do I use alsamixer to put the gain back up and save it. @ehpersonal38

[Vollpflock]

https://github.com/mcguirepr89/BirdNET-Pi/wiki/Adjusting-your-sound-card

[morrowwm]

Discussion #253 is converging on this topic.