  The geometry of a floating bridge on a drumhead soundboard produces string
stretching that is first order in the amplitude of the bridge motion. This
stretching modulates the string tension and consequently modulates string
frequencies at acoustic frequencies. Early work in electronic sound synthesis
identified such modulation as a source of bell-like and metallic timbre. And
increasing string stretching by adjusting banjo string-tailpiece-head geometry
is known to enhance characteristic banjo tone. Hence, this mechanism is likely
a significant source of the ring, ping, clang, and plunk common to the family
of instruments that share floating- bridge/drumhead construction. Incorporating
this mechanism into a full, realistic model calculation remains an open
challenge.
