Designing soundboards with flexural disk models.

Musical instruments are designed to be efficient sound radiators that can survive the rigors of the handling and use by musicians. A flexural disk soundboard and ported box system is developed to explore various structural acoustic design strategies. The flexural disk is used to link the structural and acoustic properties of the soundboard. Musical instruments are designed to reproduce a range of frequencies. The playing frequency range of an instrument is defined as being from the frequency of lowest open string to the frequency an octave above the frequency of the highest open string. The fundamental or main wood mode of a string musical instrument, plucked or bowed, is observed to be at the center of the instrument’s playing range. The main air mode is placed approximately an octave below the main wood mode. Soundboards are sized to be approximately a quarter of the acoustic wavelength in diameter at the main wood frequency. The simple flexural disk models with their linked structural acoustic properties demonstrate a solid structural acoustic logic to the empirically developed instruments and why these designs have been so resistant to change by inventive and creative contemporary instrument makers.