A Low Cost Infrasonic Recording System

Abstract

Each year more than 50 people and 150 elephants in Sri Lanka lose their lives due to the prevailing human-elephant con ict. The alarming rate of deaths has prompted the relevant authorities in Sri Lanka to attempt to mitigate the feud by erecting electric fences in the villagers bordering wild life sanctuaries. Although these death-traps were supposed to keep the two hostile parties apart, elephants have somehow mastered a few tricks to jump the fence without getting electrocuted. Furthermore, maintaining such long fences for long periods of time in remote and rural areas has become a Herculean task for the authorities. In the aftermath of the failure of electrical fences, zoologists have suggested the development of an early warning system to prevent elephant raids on villages. Various researches have been carried out by institutes the world over to nd methods to detect an approaching elephant before it becomes visible to the naked eye. One such research pointed out the possibility of using the elephant-elephant communication (elephant rumbles), which lies in the range of infrasound (less than 20 Hz), to detect the presence of a heard of elephants in close proximity. However, these sounds have to be recorded and analyzed precisely to prove their uniqueness in order to guarantee that the detection is fail-safe. Human ear is audible to sounds having frequencies in the range of 20 Hz - 20,000 Hz. Sound waves having frequencies less than 20 Hz are often referred as infrasound while frequencies above 20,000 Hz are called ultrasound. Elephants, unlike humans, use infra- sound in order to communicate with the members of their species. Therefore, zoologists are trying to determine whether infrasound emitted by elephants could be used to detect their presence. Although humans never use infrasound or ultrasound for communication, researching of these types of sounds is of utmost importance in other areas. Recording equipments that are designed speci cally to record and analyze sound waves having these frequency ranges are not commonly available. The equipments that are available are designed for special purposes and are very costly. The design is so complex, zoologist may nd them very di cult to manage and adapt to their research. Thus the primary objective of this research was to design and develop a Low Cost, User Friendly, High Precision infrasound recording system for zoologists in Sri Lanka to carryout research on elephant infrasound.