here buffer.data is Uint8List pcm data which mean the range will be 0-255

 var data = buffer.data as List<int>;
         var sum = 0;
         for(var i = 0; i<  data.length;i++){
           sum+= data[i] * data[i];
         }
         var mean = sum/data.length;
         var rms = math.sqrt(mean);
         var db = 20*math.log(rms/255)/math.ln10;
         print(db);

now when I calculate this I get values around -2 to -7 which I think is too nominal for silence and some noise with when I'm speaking.

So is this correct way?