RT60 failed measure on Iphone

[Thibault Mercier]

Hello,

I have buy and I am using audiotool or Iaudiotool on android, Iphone.
 may be  in10 différents phones.

Some of this phones are not "able" to calculate properly the RT60.

With the same mic. in the same room. with the same kind of baloon.
Some of them work perfectly.

Some of them give no information or very, very wrong RT60.
something like 0.2s of RT60 instead of 0.8s...

may be there is a calibration or a parameter to adjust ??

Thanks. Best regards, thibault

[Julian Bunn]

Hi Thibault,

That's an interesting observation. It must be something to do with the different audio hardware on the various phones. If the phone is correctly triggering to start the RT60 measurement, the SPL measurements should die off at the same rate as on a different phone. Do you observe any difference in SPL measurements between the phones, when they are subjected to the same noise/signal?

Julian

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[thibault....@gmail.com]

Hi Julian,

 

Thanks for your reply.

 

Just a word about the context.

We are a small company who manufacture acoustics panels.

We work with craftsman. And we ask them to buy the IMM-6S and download your app to be able to give us information about their customers rooms.

 

Yesterday With one of them we try it with 2 Iphone.

 

The XR, the SE 2020
both of them had a lighting extender to connect with the mic. (IMM-6s)

The mic look working as a charm at the first step. 
The SPL work correctly.

This is when we are trying to measure the RT60 that we have a problem.

The mic doesn’t seem to be activate at this step.

You can find the caption in attachment.

 

Also, we try without the mic.

There is data.

But absolutely not right. (0.2s in 100m3 room with concrete on the floor and in the walls.)

 

So we just find out an old but gold facom android phone.

And it’s seem working.

 

I remember that already happen with an xiaomi on android.

There is a couple of time when I was trying the app with my associate.

But I just let it go because he wasn’t using it and mine work perfectly.

 

So I don’t know what to think yet.

 

PS:

May be,

You are able to make a little compact product using Arduino card ?

 

 

Kind regards

 

Thibault Mercier

07 88 44 88 71

 

 

 

 

De : audiotool-dis...@googlegroups.com <audiotool-dis...@googlegroups.com> De la part de Julian Bunn
Envoyé : jeudi 22 juin 2023 22:15
À : audiotool-dis...@googlegroups.com
Objet : Re: [AudioTool-Discuss] RT60 failed measure on Iphone

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[Julian Bunn]

Hi Thibault,

If the RT60 doesn't trigger sometimes, then this could be simply because the sound of the balloon popping (or whatever you are using) isn't loud enough (or the phone is too far away).

I'd expect some sensitivity difference between the iMM6 and the built-in mic - so that could be why it triggers with one and not the other?

It sounds quite challenging to get reliable results if you have no control of which phone the customer is using; and even for identical phones there are a lot of other factors. I've not thought about this before, but does the size of the balloon and the thickness of its skin affect the intensity of the noise when it pops?

Julian

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[thibault....@gmail.com]

Hi Julian,

 

 

Thanks.

 

I think about this problem and experience it myself.

This is not a balloon problem.

One of your customer send me a MP and told me that the problem is the automatic gain control in the new smartphone.

He tell me to use an external audio card.

 

I will try when I will have the time to do it and keep you in touch if I can fin a light solution like the little mic.

 

Take a look on it, may be there is a simple hardware solution.

 

Best regards

 

Thibault Mercier

07 88 44 88 71

 

 

 

 

De : audiotool-dis...@googlegroups.com <audiotool-dis...@googlegroups.com> De la part de Julian Bunn

Envoyé : samedi 24 juin 2023 19:45

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[Julian Bunn]

Hi Thibault,

AudioTool uses the Android setting "Measurement_Mic" for the audio stream from the microphone. This is supposed to bypass all filtering and AGC. Of course, it's up to the phone's manufacturer whether their firmware for the phone actually respects this setting or not. If AGC is being applied, then that's not anything AudioTool has control over, unfortunately :-(

Julian

To view this discussion on the web visit https://groups.google.com/d/msgid/audiotool-discussion-group/008f01d9a7ff%24c706c8f0%2455145ad0%24%40gmail.com.