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Modified Wood of Black Locust - Alternative to Honduran Rosewood in the Production of Xylophones

100%

Danihelová A., Čulík M., Němec M., Gejdoš M., Danihelová Z.

Acta Physica Polonica A

2015

vol. 127

issue 1

106-109

Traditionally, exotic hardwoods are used for the production of xylophone or concert marimba. Mainly the Honduran rosewood shows the optimal properties (high density, high modulus of elasticity, speed of sound, hardness, low damping) considering the required acoustic quality of the xylophone. The Honduran rosewood is listed in CITES Appendix II, therefore it is necessary to look for possibilities of its replacement by other wood species. However, the density, hardness and strength properties of the European wood species are rated less than Honduran rosewood. Therefore it is clear that there is a need to search for alternative of exotic wood. Our research indicates that the Honduran rosewood can be replaced by European wood species; however it is necessary to modify their properties. As convenient modification of domestic wood species appear: mechanical modification (densification), thermal modification or a combination of these two methods. Thus we can obtain wood with properties similar to the properties of exotic wood. The study presents the comparison of physical and acoustical characteristics of modified wood of Black locust with the characteristics of the Honduran rosewood. Also, the sound quality of xylophone made from Black locust wood before and after modification was investigated.

Train Noise - Comparison of Prediction Methods

86%

Němec M., Danihelová A., Gejdoš M., Gergel' T., Danihelová Z., Suchomel J., Čulík M.

Acta Physica Polonica A

2015

vol. 127

issue 1

125-127

Railway noise in towns and city centres is one of the environmental problems. Defining the noise level is possible in two ways - via in situ measurement or via calculation (prediction). For the comparison of objectively measured values of sound pressure levels from railroads two methods used in the Slovak Republic were chosen - Schall 03 and the Czech prediction method. Track number 170: Zvolen-Vrútky in the town Zvolen was selected as the measurement location of noise exposure. Method Schall 03 overestimates the measurement values by approximately 1 dB and the Czech method by 4 dB. Both prediction methods, in spite of the systematic overestimating, describe the real noise situation very well; the calculated Pearson coefficient of correlation with Schall 03 method was 0.94 and with the Czech method 0.90.

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2 Acta Physica Polonica A

2 2015

2 Danihelová A.

2 Danihelová Z.

2 Gejdoš M.

2 Němec M.

2 Čulík M.

1 Gergel' T.

1 Suchomel J.

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Modified Wood of Black Locust - Alternative to Honduran Rosewood in the Production of Xylophones

Train Noise - Comparison of Prediction Methods