A LOW-COST ENVIRONMENTAL ACOUSTIC PLATFORM FOR EVALUATING HUMAN EXPLOITATION OF TROPICAL FORESTS

中美洲的热带森林正日益受到来自未知威胁的环境压力。在这些地区，通常利用卫星成像技术监测砍伐和森林火灾等干扰情况。然而，隐藏在森林树冠下的其他威胁，如非法偷猎和选择性采伐，可能会在未被发现的情况下继续进行。微控制器和表面贴装麦克风技术的最新发展意味着低成本的连续声传感现在是一种可能的解决方案。因此，我们提出了一种声学数据采集系统，以有效地监测航空摄影无法监测的人类活动。讨论了两个初步的案例研究，强调了系统硬件的可行性。第一项研究比较了两种表面贴装麦克风，观察它们对不同距离的枪声和电锯噪音的敏感度。第二部分讨论了基于低成本微处理器的硬件的优点和局限性。在这里，我们试验了一种定制设计的声波记录器，部署了三个月来检测和记录当地一种稀有的昆虫。我们的研究结果表明，该硬件是一种高效的实时检测工具，其功耗适合于长持续时间的记录。事实证明，麦克风的灵敏度也足以探测到至少半公里远的枪声。

The tropical forests of Central America are increasingly under environmental pressure from unchartered threats. In these areas it is typical to monitor disturbances such as clear-cutting and forest fires with satellite imaging techniques. However, concealed by the forests canopy other threats such as illegal poaching and selective logging can proceed undiscovered. Recent developments in micro-controller and surface mount microphone technology means that continuous acoustic sensing at low-cost is now a possible solution. Consequently, we propose an acoustic data acquisition system to effectively monitor anthropogenic activities that aerial photography cannot. Two preliminary case studies are discussed emphasizing the feasibility of the systems hardware. The first study compares two types of surface-mount microphone, looking at their sensitivity to gunshot and chainsaw noise over varying distances. The second considers the advantages and limitations of low-cost microprocessor based hardware. Here, we trial a custom designed acoustic logger over a three month deployment to detect and record a local rare species of insect. Our findings show the hardware to be an efficient real time detection tool with power consumption suitable for long duration recordings. The microphones sensitivity also proves sufficient for detecting gunshots at distances of at least half a kilometer.