التفاصيل البيبلوغرافية
| العنوان: |
Low frequency acoustic pulse propagation in temperate forests. |
| المؤلفون: |
Albert, Donald G.1 Donald.G.Albert@usace.army.mil, Swearingen, Michelle E.2, Perron Jr., Frank E.1, Carbee, David L.1 |
| المصدر: |
Journal of the Acoustical Society of America. Aug2015, Vol. 138 Issue 2, p735-747. 13p. |
| مصطلحات موضوعية: |
*ACOUSTIC pulses, *ACOUSTIC wave propagation, *FORESTS & forestry, *WAVE analysis, *POROUS materials, *REVERBERATION time, *DECIDUOUS forests, *SPRUCE |
| مصطلحات جغرافية: |
UNITED States |
| مستخلص: |
Measurements of acoustic pulse propagation for a 30-m path were conducted in an open field and in seven different forest stands in the northeastern United States consisting of deciduous, evergreen, or mixed tree species. The waveforms recorded in forest generally show the pulse elongation characteristic of propagation over a highly porous ground surface, with high frequency scattered arrivals superimposed on the basic waveform shape. Waveform analysis conducted to determine ground properties resulted in acoustically determined layer thicknesses of 4-8 cm in summer, within 2 cm of the directly measured thickness of the litter layers. In winter the acoustic thicknesses correlated with the site-specific snow cover depths. Effective flow resistivity values of 50-88 kN s m-4 were derived for the forest sites in summer, while lower values typical for snow were found in winter. Reverberation times (T60) were typically around 2s, but two stands (deciduous and pruned spruce planted on a square grid) had lower values of about 1.2s. One site with a very rough ground surface had very low summer flow resistivity value and also had the longest reverberation time of about 3s. These measurements can provide parameters useful for theoretical predictions of acoustic propagation within forests. [ABSTRACT FROM AUTHOR] |
| قاعدة البيانات: |
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