Piezo buzzer slow to sound, should i change circuit ?

Hey guys,
So im building this buzzwire game which is meant to sound a buzzer whenever the wires touch. However after assembling the circuit as shown below i realised that the buzzer does not sound instantly. I think i might need to change my circuit. I know that the output pin for the arduino sends 5v but i assume the problem is that the touches are to slight to process.

Would adding a transistor with the buzzer work?

heres the excerpt of my code which sounds the buzzer

if (digitalRead(4) == HIGH) 
  { 
    bonus += 2; 
    delay(500); // for debounce 
    Serial.println("TOUCH  TWO SECOND PENALTY ");
    if (digitalRead(4) == HIGH) {
    // Sound buzzer:
    digitalWrite(13, HIGH);
  }
  else {
    // 
    digitalWrite(13, LOW);
  }
}

Much love in advance for the help !

bonus is a strange name for a penalty, how about malus?

if (digitalRead(4)) {
  bonus += 2;
  Serial.println(F("TOUCH  TWO SECOND PENALTY "));
  digitalWrite(13, HIGH);
  delay(500);
  digitalWrite(13, LOW);
}