Acoustic characterization of doped silica glasses with a Ge02, P205, F, Ti02, A1203 or B203 dopant having different concentrations is presented. The quantitative measurements are performed by a 225 MHz line-focus-beam scanning acoustic microscope. The acoustic velocity variation due to different dopant concentrations for each dopant is given. It has been found that the A1203 dopant increases but the other dopants decrease the acoustic velocity as compared to that of the pure fused silica. The fiber preforms having step and graded refractive index profiles also show step and graded acoustic velocity profiles respectively. We have also found that the acoustic velocity is more sensitive to the dopant concentration as compared with that of optical refractive index.