Professor, do you know the bowed musical instrument - erhu, a kind of two-stringed instrument, it has a tiny bridge on the skin center, and the horsehair bow plays the strings from a crossing angle on the resonator, we find the acoustic sound changes from a lower frequency to high, the volume are not balanced, on other words, the high-frequency similar muted, I hopefully want to learn the principle, why? It's different from the drum, but it has a drum-like resonator, but the bridge on the center and two strings over the bridge produce pressure, similar to stopping the skin vibration. If you want to learn more about the musical instrument, I could take a short video. Thanks!
