Effects of seasoning on the vibrational properties of wood for the soundboards of string instruments

The vibrational properties of green spruce wood samples were measured intermittently during drying and subsequent conditioning under ambient conditions to clarify the effects of seasoning. After drying, the equilibration of mass and the sound velocity of wood continued to increase, and its internal friction significantly decreased during six months of seasoning. However, those seasoning effects disappeared once the wood was moistened at 100% RH. Physical aging and stress relaxation of wood polymers was assumed to be responsible for this effect. This coincides with the empirical knowledge of violin makers: seasoning for a few years is more important than long-term aging over centuries.