The infrared divergence response theory is applied to the two-level System model of structural defects in glasses, and the twopeak structure of the ultrasonic absorption is explained by this theory. It is reasoned out that the small low-temperature peak depends more strongly on frequency than that of the high-temperature peak. On the basis of indroducing the effective potential, a good agreement with experimental data for ultrasonic aibsorption in SiO2 is attained over the whole temperature range.