Make Touchless ANY THING using ultrasonic sensor module

1//this project is made by Circuit Mania  
2//https://www.youtube.com/channel/UCJPKa558LvFFYOL3zfEmJ9g?view_as=subscriber
3const  int pingPin = 7;
4//adjust this to set the min speed of wave gesture
5const  int waveBackWait = 5000;
6//Range of detection from the sensor in cm
7const  int range = 7;
8void setup() {
9  pinMode(10, OUTPUT);
10}
11void loop() {
12  long duration, cm;
13  pinMode(pingPin, OUTPUT);
14  digitalWrite(pingPin, LOW);
15  delayMicroseconds(2);
16  digitalWrite(pingPin, HIGH);
17  delayMicroseconds(5);
18  digitalWrite(pingPin, LOW);
19pinMode(pingPin, INPUT);
20  duration = pulseIn(pingPin,  HIGH);
21  
22  cm = microsecondsToCentimeters(duration);
23if(cm < range &&  cm > 1){
24    for(int i=waveBackWait; i>0; i--){
25      long new_duration, new_cm;
26      pinMode(pingPin, OUTPUT);
27      digitalWrite(pingPin, LOW);
28      delayMicroseconds(2);
29      digitalWrite(pingPin, HIGH);
30      delayMicroseconds(5);
31      digitalWrite(pingPin,  LOW);
32      pinMode(pingPin, INPUT);
33      new_duration = pulseIn(pingPin,  HIGH);
34  
35      new_cm = microsecondsToCentimeters(new_duration);
36      if(new_cm  < range && new_cm > 1){
37        //ring the doorbell
38        digitalWrite(10,HIGH);
39        delay(500);
40        digitalWrite(10,LOW);
41      }
42    }
43  }
44}
45long  microsecondsToCentimeters(long microseconds) {
46  return microseconds / 29 / 2;
47}