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I've already troubleshot and resolved the issue, my recording's come out well so I don't need help on that end, I just want to know how this issue that I had happened.

I have a wooden bookshelf, real wood all the way through, and I put a phone on the shelf and plugged a wired microphone into the phone. Recorded my audio/video, listened back and discovered an angry buzzing background noise that also degraded recorded sound. After troubleshooting, I found that if the point where the microphone was plugged into the phone is in the shelf, with wood above and below it, the interference happens. This problem was resolved by having the phone hang off the edge of the shelf. I am baffled though, how would an empty wooden shelf make something like this happen?

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    More likely proximity to AC voltage than the wood itself.
    – Tetsujin
    Dec 30, 2021 at 11:04
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    wood does not interact with electrical or magnetic fields, hence it is something else, other than the wooden shelf doing this.
    – Mark
    Dec 31, 2021 at 0:14
  • @Tetsujin The shelf is empty, do you mean like power running through the wall was causing the interference?
    – day
    Dec 31, 2021 at 12:27
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    Possibly. It's not going to be the wood alone -wood is to all intents & purposes completely inert as regards electromagnetic interference or propagation.
    – Tetsujin
    Dec 31, 2021 at 12:29
  • A guess: Put a piece of fabric between the phone and wood below. The phone stops making microscopic hits against the wood when the wood slightly vibrates mechanically due traffic, loud sounds around, some machine in the house etc...
    – user35252
    Jun 7, 2022 at 7:13

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You describe an "angry buzzing background noise". I'm not sure what sound quality is meant by this. Lower buzzing, more like humming, points towards the possibility of a mechanical cause. Higher buzzing, like sizzling, is an indicator for an electrical cause.

In case of "lower buzzing" : wood is a very good transmitter of vibrations. So if your phone had physical vibrations, a book shelf might well pass them on to the microphone. The only thing is: what mechanical parts of a phone would cause these vibrations? I'm not aware of any. Anyway, the solution to this issue is decoupling the mic and/or phone from the shelf physically. This might be either by letting one of them hang down or use some foam in between.

In case of "higher buzzing", perhaps, the reason is an electromagnetic interference, to which the book shelf is "agnostic". The solution here is to adjust the alignment of the two devices so that the magnetic field of the phone does not affect the microphone. This is trial and error. Turn a bit here and there, increase the distance, until you have a satisfying result.

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  • I've actually already solved the issue, but created this question because the cause baffles me. My ultimate solution is to have the phone on a stand suspended a little bit outside of the edge of the shelf, with the mic plugged in like that, which eliminates the buzzing. The buzzing feels like the buzzing of a speaker that's not quite plugged in right, which was what led me to suspect some kind of interference
    – day
    Jan 6, 2022 at 11:38
  • That kind of buzz is "60-cycle hum" which gets picked up from electromagnetic signals in the air caused by AC power (the wiring in your walls, mostly.) If you move the wood cabinet and put the phone in the same place, it'll buzz. It's not the wood, it's the location. Find a better location! Oct 7, 2022 at 15:22

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