Galaxy A52s — known issues?

[Klaus]

Hello!

I am trying to use Audiotool to measure noise levels in a neighborhood conflict.

I was able to get to a point with Google Gemini. But I have run into issues where I need human feedback.

• I have calibrated the main mic with a professional device at around 55 dB(A), which gave me an offset of -11.5 dB.
• I have a Dayton Audio iMM-6C. However, when installing the calibration file I get unrealistic 45 dB(A) as the noise floor (quiet room, microphone and phone under multiple layers of blanket), so there seems to be some artificial gain added to the Dayton.
• According to OboeTest, my phone supports the "UNPROCESSED" Sound source setting.
• The Dayton occasionally show a peak 10–15 dB(A) higher than the final value at the beginning of a measurement (Chat view), so I am worries that some noise suppression is active. The effect was most visible when using a white noise generator app on my laptop as a reference.
• With the main mic this initial drop (after closing an reopening the app) is *not* present for a loud source but may appear for lower sound pressure levels (< 50 dB(A)).
• When measured after midnight in a room quiet enough to hear heating pipes and the noise floor of my own ears, measuring under a blanket gives noise levels on the scale of <10 dB(A) — far below a realistic noise floor for even professional equipment.

Any ideas what I could do to get useful values?

[Julian Bunn]

I'd recommend purchasing an SPL calibrator, like this one: https://www.amazon.com/Decibel-Calibrator-Calibration-Measurement-Microphones/dp/B0786YDF62

just so that you know the absolute dB levels you are measuring with the iMM6 make sense. The Dayton cal file is only for adjusting relative levels as a function of frequency, not for adjusting absolute values.

Other people on the list may have more useful advice on your measurements.

Julian

[Non Timebo Mala]

All this noise measuring you're doing is going to be useless in court because you're not going to have reference levels.  In other words think about it like this decibels mean nothing to the judge.  Now if you go out in the street and you measure traffic driving by and you get a level then you will be able to say to the judge the traffic level by my phone is so many decibels.  This chart here that I got from the internet says that this many decibels is what traffic is.  Let's say it's 70 decibels.  Well then I went over to my neighbors fence and I measured it and it was 90 decibels.  You see this chart here says that traffic is actually 77 decibels and my phone only measured 70 so that means that this measurement at 90 is really 97 and if we look at the chart we will see that 97 is too damn close to an airport.  And that is how you're going to have to make your argument because the judges ears are not calibrated in decimals they're calibrated in airport.  Think about it before you walk into that courtroom with a bunch of numbers that don't mean the damn thing to the judge.

https://keys.mailvelope.com/pks/lookup?op=get&search=0xF77691B7C3A881FE

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[Ian Eales]

+1 on the calibrator. If you get one for a 1/2 inch mic, you can make an adapter with a bit of plastic hose from the hardware store to fit the imm6

It would help to know what phone / OS as they likely operate differently.

I found that regardless of which mic is active, plugging in the imm6 is active.

I recommend creating a nul cal file and always loading that at app start up. If you have a cal file loaded and change mics it remains in process.

To create a nul cal file just start to create a cal file and save it as nul.cal with all zeroes. Then Finish calibration.

[Klaus]

Is it possible to merge this thread with my other post? On mobile it looked like THIS thread was just not posted, the message about "posted but not approved" wasn't shown — and the new thread contains more details.

[Klaus]

For reference, I don't need it for court, but for a discussion with the neighbors. Under the Austrian legal framework, in front of court only a court-ordered expertise really counts, and with that we'd be talking about EUR 4,000–5,000 after tax. The measurement would primarly be intended for further discussion to estimate whether the neighbors' complaint has merit and should be taken seriously, or whether I have to say "you expect unrealistic things, but I can't stop you from sueing". 

[Klaus]

Regarding the calibrator: I try to avoid costs here, or my wife will have my neck for it. I had a chance to compare my phone's main microphone with the calibrated device of a city official (gave a single-offset of −11.5 dB(A)), but I have since accumulated some concerns about the presence of digital filters that may make a calibration pointless. 

That's in more detail in the accidental duplicate thread though. 

[Klaus]

Hello!

I am merging the comments so far over in the newer thread:

Galaxy A52s: Unavoidable noise suppression, even with Dayton Audio iMM-6C?

[Klaus]

I have merged the comments from here to the newer thread with screenshots:

[Galaxy A52s: Unavoidable noise suppression, even with Dayton Audio iMM-6C?]