AAR-04 (ATmega 328p) freezes upon constructing class

I wanted to create a library for my robot’s ultrasonic sensors, since I have more for obstacle detection. My sketch compiles and everything, but when I open the Serial monitor to check if my program is running, it only puts out “⸮s”. Has anyone suggestions?

/*
  Klassendatei um sich die doppelte Schreiberei und im Endeffekt auch Lesearbeit zu sparen.
  Für den AAR-04 konzipiert, da es zwei identische Ultraschall-Sensoren gibt, aber natürlich umso effizienter, desto mehr Sensoren.
  ~ Steffen Eilers
*/
#ifndef ultrasoundClasses_h
#define ultrasoundClasses_h
#include "Arduino.h"
class Ultra
{
	public:
	 Ultra(int trigPin, int echoPin);
   void ultraDistancePrint();
	 long duration;
	 int distance;
	private:
	 int _trigPin;
	 int _echoPin;
};
#endif
//#include <PinChangeInt.h>
#include "ultrasoundClasses.h"
Ultra ultra(8,4); 

void setup() {
//Serial.println("ahahahahahahahaha");
}

void loop() {
ultra.ultraDistancePrint();
Serial.begin(9600); 
Serial.println(F("Test"));

}
#include "Arduino.h"
#include "ultrasoundClasses.h"

Ultra::Ultra(int trigPin, int echoPin)
{
  _trigPin = trigPin;
  _echoPin = echoPin;
  pinMode(_echoPin,INPUT);
  pinMode(_trigPin,OUTPUT);
}
void Ultra::ultraDistancePrint(){
  /*// Clears the trigPin condition
  digitalWrite(_trigPin, LOW);
  delayMicroseconds(2);
  // Sets the trigPin HIGH (ACTIVE) for 10 microseconds
  digitalWrite(_trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(_trigPin, LOW);
  // Reads the echoPin, returns the sound wave travel time in microseconds
  duration = pulseIn(_echoPin, HIGH);
  // Calculating the distance
  distance = duration * 0.034 / 2; // Speed of sound wave divided by 2 (go and back)
  // Displays the distance on the Serial Monitor
  Serial.print("Distance left: ");
  Serial.print(distance);
  Serial.println(" cm");
  Serial.println("in Klasse");*/
  
}

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