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I am preparing a DIY home recording studio. I did four experiments a new Samson C01U plugged into a Mac computer and recording into Audacity. I recorded background noise in one room without furniture and with a lot of echo; in the adjacent room with furniture and 5 foam mattress; in the closet of that second room; and in that room with more foam padding around the microphone.

I analyzed the noise level with

ffmpeg -i recording -af loudnorm=I=-24:TP=-9:LRA=7:print_format=summary -f null -

The noise in the closet is:

mean_volume: -80.8 dB
max_volume: -67.4 dB

The noise in the three other locations is the same at the decibel decimal level:

mean_volume: -83.3 dB
max_volume: -70.3 dB

To make sense of these numbers, I hypothesize that the main source of noise in the three room settings is the self-noise from the microphone and the noise from the Mac computer, and that this noise is reverberated in the small closet and increases the noise level by 3 dBs.

The Samson C01U data sheet does not mention self-noise. An Amazon.com page for Samson C01 mentions "Self Noise: 23 dB", so I can't immediately judge this number compared to the average volume of -83.3 dB. The microphone has a hypercardiod pattern and the computer is to the side.

Is this true? Or should I pad the room with more foam to decrease the level of background noise?

Update: On a different day, I did the same test and got more variation in the results: mean volume between -67.2 and -69.2 dB and max volume between -52.7 and -56.2 dB. Having the laptop inside or outside the room made only a 0.2 dB difference in the mean volume. So maybe the ambience is the main source of background noise, especially as the recordings are half a kilometer from the beach and the wind and waves are strong today.

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    The Mac will be far higher noise than the mic's noise. If you are serious about trying to reduce noise floor, take the computer out of the room, and only have the mic in the room.
    – Rory Alsop
    Oct 3, 2020 at 14:24
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    Are you going to be doing rock vocals or whispered voiceover? I'd only even vaguely worry if it's voiceover. Singing really should have enough level that you will simply never notice. Quiet voiceover with no other audio track, I tend to drop iZotope into the chain to clean it up, otherwise I've never cared. You'll get more spill from the cans than the puter fans, unless you've got a laptop with fans revving hard.
    – Tetsujin
    Oct 3, 2020 at 15:53
  • @RoryAlsop I added the hypercardiod pattern in the question and results from the computer inside the room. Oct 7, 2020 at 13:18
  • @Tetsujin The recordings are for vocals. Thanks for the tip on iZotope, it's not available for my Digital Audio Workstatioin. Do you use it on hardware? Or which software? Oct 7, 2020 at 13:19
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    I use iZotope with Cubase. I think they have a list of platforms on their site. Pretty certain you can run it stand alone as well.
    – Rory Alsop
    Oct 7, 2020 at 13:20

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