13 Tuning the bridge:
The bowed string produces a wide range of vibrational frequencies. The highest of these lack the energy to pass through the bridge and excite the body of the violin to produce an audible sound. Thus the bridge could be regarded as a tonal filter cutting out higher frequencies. As wood is removed from the bridge, a greater portion of the higher frequencies from the string pass through the bridge and the violin's tone is "brightened". The response of the instrument also improves. As more wood is removed, "brightness" turns to "harshness" and the bridge becomes structurally weak.