Question about piezzo buzzer

Hi,i am just curious to know why is the sound different (louder?) when the hole on the buzzer is obstructed.

https://www.youtube.com/watch?v=DhvQd5AVKSE&feature=youtu.be

void setup() 
{
  pinMode(2, OUTPUT);
}

void loop() 
{
  tone (3,1000,100);
  digitalWrite(2, HIGH);
  delay (500);
  digitalWrite(2, LOW);
  delay (500);
}

Probably the piezo is reflecting the sound into the breadboard which then becomes a sound board. Note, you are calling this a piezo buzzer, is this a buzzer or a piezo speaker?