Resonance wood microstructure peculiarities
In researches there are contradictory conclusions about interconnection between macrostructural and acoustic characteristics of sounding timber. Unfortunately, there are only a few works of such kind and all of them are of sporadic nature, which give evidence of necessity to continue such researches both at the level of macrostructure and microstructure. The aim of the research is to reveal the peculiarities of sounding timber microstructure, thanks to which it combines two incompatible, at first sight, parameters: High modulus of elasticity (rigidity) and low density. As a result, sounding timber differs from ordinary one in its unique acoustic characteristics, especially in delicacy and timber of sounding. The research results were obtained through applying an electronic scanning microscope to 360 constant and temporary specimens. For this purpose, 800 timber cuts were made in transversal, radial and tangential directions of a tree stem. Besides, macerated material was used to define early and late tracheids length. In the course of the experiment the increment layers width, the number of tracheids in a radial row of early wood, the number of tracheids in a radial row of late wood, the radial and tangential diameters of early and late tracheids, the thickness of tracheids radial and tangential walls in early and late wood, the quantity of vertical resin ducts and their diameter, the height and number of plies in linear (single-row) rays, the height and number of plies in fusiform rays, the diameter of a horizontal resin duct, the quantity and diameter of rounded bordering pores on tracheid walls were studied. The research results revealed a number of differentiating characteristics of sounding spruce timber microstructure.