For the first time, scientists have experimentally demonstrated that sound pulses can travel at velocities faster than the speed of light, c. William.
So we all know that the speed of sound increases with greater density of medium. Conversely, the speed of light decreases with greater density.
A group of high school and college teachers and students has transmitted sound pulses faster than light travels -at least according to one....
What travels faster than speed sound - journey
Sound breaks the light barrier. However, this effect is not as large as the velocity differences due to the change in reference frame. The pressure wave bouncing off the plane would be traveling at the speed of sound if it didn't run into the shock wave, which travels slower than the speed of sound relative to the exiting air which is on the plane side of the shock wave.