Sound Attenuation in Pregnant Sheep Measured by Intrauterine Microphone

Hermanto, Komang, Diah, Djamil 2003

Abstract

Aims: To measure the sound attenuation of external sound by the abdominal and uterine wall of pregnant sheep.

Methode: Experimental study, 2 pregnant singleton term healthy sheeps after ethical clearance. Independent variables were external sound in multifrequency and multi intensity, dependent variable was sound intensity measured by intrauterine microphone. In general anaesthesia, the microphone was inserted inside the uterus without breaking the amnionic wall through the abdominal and uterine wall. Basic sound levels were recorded and then external sound exposed and recorded intrauterinely at frequency of 31,5, 63, 125, 250, 500, 1000, 2000, 4000, 6000, 8000 Hz and intensity of 80, 85, 90, 95 and 100 dB respectively. The exposed and intrauterine sound were recorded simultaneously. All data were processed by Soundforce program(@) in Pentium 3 hardisk and the intensities were measured by sound level meter.
Settings: Veterinary Hospital, Faculty of Veterinary Airlangga University Surabaya.

Results: The basic intrauterine sound levels were between 43 – 58 dB at frequencies of 31,5 – 8000 Hz. The external sound in all frequencies were attenuated. The average differences between the intensity of external and recorded sound in two sheeps was 16,757 ±8,07787, which was statistically significance (paired t test). Sound attenuation at frequency of 2000 – 8000 Hz were bigger than frequency < 2000 Hz.

Conclusion: This study showed that the external sounds were attenuated by abdominal and uterine wall at all range of frequencies and intensities. This confirmed the hypothesis that the musical stimulation to the mother- in the next studies, must be placed in the abdominal wall of the mother in order to decrease the attenuation effect.

Keywords: Sound Attenuation, intrauterine microphone, pregnant sheep