Study of evaluation of natural environment preservation by the measurment of the natural environmental sound

我们的立场是，所有的声音都被重新考虑为“环境声音”。然后按一种将“环境声”分为“生活环境声（人工声源）”和“自然环境声（非人工声源）”。特别是对“自然环境声”的观测案例较少，目前普遍没有确定观测方法和评价方法。在天然林（自然环境的丰富空间）中，采用噪声测量法对自然环境声进行观测。此外，还通过树木普查和地形调查对声音结构进行了调查。采用易于与生活环境声进行比较的等效噪声级作为自然环境声的评价值。在调查适用区域设置三个观测点。从三个不动点观测的结果中，我们可以掌握等效噪声电平的特征和方差。通过这些结果，提出了指数化的可能性。通过对林分普查调查的林分进行分析，提出了一种聚类的可能性。

We take a position that all sound is reconsidered as "an environment sound" by this research. Then it is separated "an environment sound" into a "living environmental sound (artificial acoustic source)" and a "natural environmental sound (non-artificial acoustic source)" by a kind. Specially, there were a few observation cases for the "natural environmental sound", generally an observation method and an evaluation method aren't decided at present.A noise measurement is used for the observation of the natural environment sound in the natural forest (the rich space of the natural environment). In addition, it is investigated about a sound structure by a tree cesus and a topographical survey. The equivalent noise level which was easy to compare with a living environment sound was adopted as a value of the evaluation of the natural environment sound.Three observation points are installed in the investigation applicable area. We could grasp a characteristic and a variance about the equivalent noise level from the result of three fixed-point observations. By these results, the possibility of index-ization was suggested. About grasping of the sound structure in a forest, a possibility of clustering is suggested by an analysis of the forest stand which was investigate by the tree census in field of forest science.