The invention discloses a plate membrane string concord
resonance type bass string instrument which comprises a
resonance chamber, an instrument rod, a
skin membrane, bottom feet, a bridge, a tailpiece, an outlet, a pattern board, a string pillow and an instrument shaft. A board membrane
resonance mode is adopted by the
resonance chamber, the upper portion of the front face of a cavity is in soundboard vibration and the lower portion of the cavity is in
skin membrane vibration through the resonance of the bridge, a sound beam and a column
loudspeaker, and a long rectangular slit, namely, a sound-output hole is reversed at the junction of two materials in the middle. The middle of the front face of a cavity is a main vibration area of pronouncing of the cavity. The bridge is driven to vibrate through vibration of four strings, and an upper sound board and a lower
skin membrane are driven to vibrate at the same time to achieve the recombination of the double sound effect. The plate membrane string concord resonance type bass string instrument has the advantages that when the sound board and the
skin membrane are vibrated in a concord mode through the bridge, the sound beam and the column
loudspeaker, similar physical characteristics should be presented; the setting of the four strings and effective
string length enables performance techniques to be simple; the vertically-and-horizontally staggered bridge mode and the geometric performance of the bridge improve the
sound quality of concord resonance; due to the fact that the board and the membrane are properly utilized to enable the sound-output holes to be formed in the junction of the board and the membrane, the recombination mode of vibrated audio signals of the board and the membrane is defined.