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Today I recorded an interesting sound that I accidentally found since the quarantine was set up on Spain. Doesn't matter the hour of recording because this interference can be recorded everytime, I have a few questions about this sound.

By the way, sound was recorded with a Tascam DR 05 V2 pointing at closed window at maximun amplified possible , this is not from outside but I tried to record outside and it keeps hearing. It sounds only in an specific places on both internal microphones, this kind of sound is very directional .

Questions:

- Can my recorder be broken ?

- Can this sound be a radio interference ?

- If this is a radio interference what kind of signal is that ?

- Any nearly accurate guess about this sound ?

THE SOUND : https://freesound.org/people/bolkmar/sounds/511890/

bolkmar wrote:
- Can this sound be a radio interference ?
...

THE SOUND : https://freesound.org/people/bolkmar/sounds/511890/

Sounds like RF interference, e.g. ... https://youtu.be/Ade7L5Jh2gM

Cellphone interference 3g 4g

bolkmar wrote:

- Can my recorder be broken ?

I'm not sure about that, but I know that the Tascam DR-05 is having multiple quality problems, especially like this. My friend owns couple of them and we've discussed many times about the problems. For example, if you are recording interview in room that has fluorescent lights and the lights are on, the recorder gets interference. I've never had any problems like this with my Zoom or Olympus recordes.

Very much sounds like cell phone interference.

Experiment 1: Wrap aluminum baking foil around your recorder, tucking in so no gaps, while recording and see if it diminishes.

If it doesn't your microphone cable is probably acting like an aerial (Even the best screened mic cable in the world will do this if the pre-amp input stage is poorly designed).

Experiment 2: Find an old computer cable that you don't use - (old monitor cable good candidate) with a cylindrical "lump" on it and see if you can cut it off. Most are two halves of ferrite material in a molded plastic cover and can be cut out with a sharp knife. Tape the two half ferrites around the mic cable close to the recorder end. (Clip-on in line cable interference suppressors are not expensive.)

Sure everyone here would love to know if you find an answer.

Stay safe,

Wibby.

Edit: Sorry, I'm very old now. Just re-read and noticed you said internal mics. Experiment 2 pointless for you but might be useful hint for others. so not deleted.

Edit 2: Leave window gap in foil for mics? These are just experiments and I realize they're poor practical solutions.

It might be a Wi-fi router or bluetooth device.

Go round house switching things off?

Keep staying safe,

Wibby.

It could also be the interference of the recorder itself. Like cellphones and wifi routers, an audio recording device creates electromagnetic sounds by itself.
Recording digital audio to a memory card creates electromagnetic sounds that can be picked up by a simple coil pickup. (example: https://jezrileyfrench.co.uk/coil-pick-ups.php)
So it could well be the sound of your recorder recording.
The fact that you notice it is maybe because the noise floor of your environment is lowered due to the covid 19 quarantine.

First of all I will give thanks to everyone who help me in this post. With that said I'll group most of users to try to reply because you give me an answer in a similar direction

@Timbre , @klankbeeld , @lartti , @strangley_gnarled , @soundslikewillem

I guess it have a lot of sense to be cellphone interference because now there're a lot of people using 3G 4G networks and the sound is similar to the captured on the video that @Timbre showed. The most interesting thing that happen when I recorded this sound is that those interferences were located in certain spots of my room window.

@strangely_gnarled

Everything checked with wi-fi, router, cellphones, etc. It only happens on my room window. Maybe it is the internal mics cable like you were pointing at this possibility , I will try your experiment.

bolkmar wrote:
... It only happens on my room window ...

If the window-frame is metal, that could concentrate the radio-waves in a spot ...
https://wikipedia.org/wiki/Reflective_array_antenna
https://wikipedia.org/wiki/Diffraction#Circular_aperture

If you do a test recording wrapped in foil (or inside a metal 'biscuit tin' or any other Faraday cage) and the interference stays or gets worse then it's coming from circuits inside the recorder. If it stops then the interference is external. Either way is a clue.

Some modern window glasses are "solar": made with a possibly metallic heat reflecting transparent coating to meet building energy efficiency standards. This fits with Timbre's 'aerial' theory.

Wibby.

Edit: My mobile phone barely works in the rooms with 'solar' double glazed windows, but signal quite strong in old single glazed kitchen. Might be just coincidence.

strangely_gnarled wrote:
If you do a test recording wrapped in foil (or inside a metal 'biscuit tin' or any other Faraday cage) and the interference stays or gets worse then it's coming from circuits inside the recorder. If it stops then the interference is external. Either way is a clue.

I tried this experiment and fortunately it was only an external interference.

To me, it sounds very much like a powerline adapter - a fiendish device designed to enable a network to be constructed using the household electricity wiring.

The big problem with these is that they radiate a high electromagnetic field which interferes with radio reception, particularly in the shortwave band. I had a pair installed a couple of houses away from me and they wiped out radio for me (Amateur radio), and the sound was very much like your recording.

A representative from our local regulatory body (OFCOM) popped out, identified the source and stopped it.

Another possibility is something associated with the mobile phone network.

I hope you get it sorted.