Suppose you are asked to hear a sound at two levels of loudness, say 80 dB and 83 dB. By what factor the sound intensity increases if the loudness of the sound increases from 80 dB to 83 dB? A problem about ultrasound device used in medical diagnostics: Given that the fetal heart wall is moving at 4 x 10-4 m/s. Now if the ultrasound probe generates ultrasound waves at 2 MHz, what frequency shift must the machine be able to detect?