Talking Doll - Microphone volume analysing

Hi,
I’m trying to do a Talking doll app.

I don’t know where to start with analysing the audio recorded.

Here is what I need :

Start Microphone

while (Microphone volume > minVolume  !audioclip.isplaying) // is the player talking?
{ 
   record to audioclip;
   if (Microphone volume < minVolume) // did the player stop talking
   {
      stop recording to audioclip;
      play audioclip;
   }
}

I started with :

source.audio.clip = Microphone.Start("Built-in Microphone", true, 10, AudioSettings.outputSampleRate);
while (!(Microphone.GetPosition(null) > 0)) {}
if (!source.audio.isPlaying) source.audio.Play ();

But I have an echo as it records while playing.

how can I analyse microphone volume to Start / Stop recording ?

I thought about analysing a temp audioclip and copy the high volume data to the final audioclip then playing it. Is it possible to analyse an audioclip without playing it?

hello???