Really nothing.
No, X-rays do not travel at the speed of sound. X-rays are a form of electromagnetic radiation that travel at the speed of light, which is much faster than the speed of sound.
The loudness of the sound has no effect on its speed.
We can use ultrasonic planes. They can travel with that speed.
In air, the seismic waves(P-wave) are simply sound waves, and travel with the speed of sound (approx. 335 m/s).
The speed of a sound wave increases when it passes from air into the ground. This is because sound waves travel faster in solids than in gases, due to the higher density and rigidity of the solid material.
At the temperature of 20°C the speed of sound is 343 m/s.
There is currently no commercial airliner which can travel at that speed.
No, the speed of sound is not dependent on frequency. It is determined by the medium through which the sound waves travel.
The sound barrier
No. Light travels at about 875 thousand times the speed of sound.
They don't really travel at the same speed, but, on television, the distance they travel is so short, that the difference between the speed of sound and the speed of light is almost non-existant.
No. The fastest speed a tornado has peen known to travel is 73 mph, about 1/10 the speed of sound. The fastest wind speed ever recorded in a tornado was 302 mph, still less than half the speed of sound.