A comparative study of the transmission parameters of the sound of mosquito predators and EMR

Abstract

The wide bandwidth EMR ultrasound, exploited in mosquito repellency, yielded only 20 % effectiveness. Due to this wide bandwidth, ultrasound from Amolops tormotus and Coleura afra, mosquito predators, was investigated. The sound was recorded, filtered and anaysed by Avisoftsoftware; transmission parameters determined and compared with those of EMR. Spectrogramanalysis showed harmonics, FM and CFcomponents.The fundamental frequency ofA. tormotus and C. afra sound was 5.371 kHz and 6.836 kHz respectively. The bandwidth of unfiltered sound of A. tormotus and C. afra was 10.98 kHz and 17.71 kHz respectively. The maximum peak amplitude of unfiltered sound of A. tormotus and C. afra was 135.19 dB SPL and 134.97 dB SPL; maximum acoustic energy was 19.57 Pa2 s and 35.80 Pa2 s respectively. Maximum acoustic energy of A. tormotus and C. afra sound was 10.843 Pa2 s and 14.857 Pa2 s recorded in 35-60 kHz and 10-34 kHz ranges respectively. Optimum acoustic parameters included 58.5 kHz peak frequency, 12.32-10.84 Pa2 s acoustic energy, 19.40-19.85 kHz bandwidth, 55.13-55.48 kHz and 34.66-44.26 kHz as mean maximumand minimum frequency respectively, 134.08-134.28 dB SPL peak amplitude and 132.06-133.27 dB SPL minimum peak amplitude; bandwidth significantly narrowed from EMR. These parameters are critical in realizing effective EMR.