[Experiment2] Blocking the Holes in the Metal Frame

If you take a look inside the piano, you can see holes in the metallic frame. What effect do they have on the sound and how does it change when these holes are blocked? We made cardboard covers and tested the sound produced when these covers were in place.

Results

*The sound recorded in the experiments differs from the actual musical pitch.

If you look closely, you can see that the outer circumference of the holes slopes upward toward the center from the flat surface of the frame, and the rim has a curved lip. With the holes unblocked, the sound had a sustained resonance and a full, rounded tone. When the holes were covered, the sound lacked brightness and luster, and felt slightly dull.