Hearing Range Analysis of Rattus Argentiventer the Paddy Field Pest

Abstract

Rice is the second most-grown cereal crop and one of the important staple foods in Malaysia. Seasonal rodent attacks from a family of Rattus argentiventer have shortened rice production by up to 80%. Yet, the acoustical method in controlling rodent populations is one of the topics that have not been properly explored. Under the field study radius, this study aims to analyse the hearing range of R. argentiventer under a controlled environment. Knowing a rodent’s ability to hear is essential for evaluating whether human activities, especially in terms of noise pollution, have an impact on hearing and consequently on rodent behaviour.  Thirteen subjects were randomly cage-caught in the paddy field and were tested in a reward-based go/no-go procedure. Fully trained subjects were observed after acoustically exposing the subjects to a 10 kHz of pure tone less than 60 dB SPL for 25 sessions. Hearing range analysis commenced by revealing a pure tone to the fully trained subjects at low (1 kHz – 5 kHz), median (10 kHz – 40 kHz) and high (45 kHz – 80 kHz) frequencies. The results showed the subjects have sensitive frequencies at 5 kHz for low frequency, the median frequency at 25 kHz and high frequency at 45 kHz. From the sensitivity hearing results, it can be indicated that the hearing range of R.  argentiventer is between 1 kHz to 55 kHz at sound levels of 60 dB. The results responded to the lack of timely response which is within an average of 5 sec and the minimum licking period at an average of 13 sec as the inaudible cut-off hearing range.