ultrasonic_sensor_with_tone.ino

int tonePin = 4;
int trigPin = 9; 
int echoPin = 10;  

int proximity=0;
int duration;
int distance;

void setup() {
 //Serial Port
 Serial.begin (9600);
 pinMode(trigPin, OUTPUT);
 pinMode(echoPin, INPUT);
 pinMode(tonePin, OUTPUT);
}

void loop() {
 digitalWrite(trigPin, HIGH);
 delayMicroseconds(1000);
 digitalWrite(trigPin, LOW);
 duration = pulseIn(echoPin, HIGH);
 distance = (duration/2) / 29.1;

 proximity=map(distance, 0, 45, 8, 0);
 Serial.println(proximity);

 if (proximity <= 0){
   proximity=0;
 }
 else if (proximity >= 3 && proximity <= 4){
   tone(tonePin, 200000, 50);
 }
 else if (proximity >= 5 && proximity <= 6){
   tone(tonePin,20000, 100);
 }
 else if (proximity >= 7 && proximity <= 8){
   tone(tonePin, 20000, 200);
 }
 delay(600);
 noTone(tonePin);
}