Question: What does the speed of sound depend on?

Answer: It depends on the density and temperature of the medium that the sound in traveling through.

Question: Density

Answer: In high density medium, sounds travels faster.

Question: Temperature

Answer: At higher temperatures sound travels faster.

Question: Sonic Boom

Answer: The loud sound wave produced when an airplane travels faster than the speed of sound.

Question: Doppler Effect

Answer: As an object is coming towards you the sound you hear is higher pitch. As the object goes away from you the sound is lower pitch.