const int pingPin = 8; // Trigger Pin of Ultrasonic Sensor 
const int echoPin = 9; // Echo Pin of Ultrasonic Sensor 
const int buzzerPin = 11; //
void setup() {
Serial.begin(9600); // Starting Serial Terminal
pinMode(buzzerPin, OUTPUT); 
}
void loop() {
long duration; 
pinMode(pingPin, OUTPUT); 
digitalWrite(pingPin, LOW); 
delayMicroseconds(2); 
digitalWrite(pingPin, HIGH); 
delayMicroseconds(10); 
digitalWrite(pingPin, LOW); 
pinMode(echoPin, INPUT); 
duration - pulseIn(echoPin, HIGH); 

while(duration<7000){
Serial. println(duration); 
int i=duration/20; 
digitalWrite(buzzerPin, HIGH); 
delay(i/2); 
digitalWrite(buzzerPin, LOW); 
delay(i); 
break; 
}
}