How to listen earpiece audio changes?

I do a voice chat program, said the two sides have been able to speak up. The sound emitted from the other handset. I want to listen to the audio receiver and the signal strength is displayed. For example, the other one to speak, there will be a dynamic flashing sign on the sound according to the size of the screen. Is like this.

My idea is to use a Timer every 100 milliseconds to check the current output earpiece volume. The output volume specifically how to detect?

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Too deep, learning ..... I look at it for you top
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cited landlord zhilongquan6 reply:

I do a voice chat program, said the two sides have been able to speak up. The sound emitted from the other handset. I want to listen to the audio receiver and the signal strength is displayed. For example, the other one to speak, there will be a dynamic flashing sign on the sound according to the size of the screen. Is like this.

My idea is to use a Timer every 100 milliseconds to check the current output earpiece volume. The output volume specifically how to detect?

In fact, that is not profound, thank you support, learn from each other!
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The landlord did not realize that I now have the same needs, seeking guidance