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Official Journal of the Japan Wood Research Society

Table 1 Average sound absorption coefficient of three softwood species at 2000–5000 Hz before and after microwave treatment depending on anatomical direction

From: An experimental study on changes in sound absorption capability of spruce (Picea sitchensis), Douglas fir (Pseudotsuga menziesii), and larch (Larix kaempferi) after microwave treatment

 

Spruce

Douglas-fir

Larch

Transverse

Radial

Tangential

Transverse

Radial

Tangential

Transverse

Radial

Tangential

Control

0.159

0.038

0.041

0.151

0.042

0.036

0.191

0.043

0.036

− 0.039

− 0.014

− 0.014

-0.036

− 0.013

− 0.014

− 0.043

− 0.013

− 0.014

Microwave treatment

0.17

0.046

0.054

0.187

0.05

0.054

0.223

0.059

0.05

− 0.043

− 0.014

− 0.013

− 0.043

− 0.014

− 0.013

0.05

− 0.013

− 0.013

ta

− 33.6**

− 21.2**

− 29.4**

− 70.8**

− 21.3**

− 42.0**

− 63.9**

− 35.1**

− 33.2**

  1. Numbers in parentheses are standard deviations
  2. at value
  3. **p < 0.001