Making Arduino count time under the stimuli

Projects Programming
1

Hi everyone, I am hoping to make my arduino count time under stimuli and I need your help.
I want to make my arduino turn on the light by servo-motor when my phone alarm rings.
But since it should not turn it on any random sounds, I want to make it move after 10 seconds of consecutive noise.

#include <Servo.h>
Servo myServo;
int threshold=1000;
int sound;
int i=0;

void setup(){
  myServo.attach(11);
  myServo.write(0);
  Serial.begin(9600);

}

void loop(){
  sound=analogRead(A0);
  int ValA0=analogRead(A0);
  Serial.println(ValA0);
  if(sound >= threshold){
    i++;
    if(i=20){
      myServo.write(180);
      i=0;
    }
  }
}

this is my code, but it seems it doesn't work.
I try to add 1 in integer 'i' whenever sounds larger than certain threshold come and
if i becomes 20, I tried to make the servomotor move.
I know even if it does work it contains problems like it cannot count sounds in serial, but
in this stage, I don't even know why this basic function doesn't even work.

Can you give me a help?