float duration_us, distance_cm;

void setup() {
Serial.begin (9600);
pinMode(2,OUTPUT);
pinMode(3,INPUT);
pinMode(4,OUTPUT);
pinMode(5,OUTPUT);
pinMode(6,OUTPUT);
pinMode(7,OUTPUT);
}


void loop() {
digitalWrite(3, HIGH);
delayMicroseconds(10);
digitalWrite(3, LOW);

duration_us = pulseIn(2, HIGH);

distance_cm = 0.017 * duration_us;

Serial.print("distance: ");
Serial.print(distance_cm);
Serial.println(" cm");
delay(500);

if(distance_cm > 10){
digitalWrite(6, HIGH);
digitalWrite(5,LOW);
digitalWrite(4,LOW);
noTone(7);
}

if(distance_cm < 11){
digitalWrite(5, HIGH);
digitalWrite(6,LOW);
digitalWrite(4,LOW);
tone(7,300);
 
}

if(distance_cm < 3 ){
digitalWrite(4, HIGH);
digitalWrite(6,LOW);
digitalWrite(5,LOW);
tone(7,1000);  

}

}