If you were on a plane going a hundred times faster than the speed of sound and you were talking to someone sitting ten rows in the back and in the front of you, how would you hear them? What about the speed of light, how would you see them?

First scenario, sound.

Because you are in a plane you are in a fairly sealed environment. The air around you is traveling roughly at the same speed you are traveling. As such, all sound and speech within the plane would appear normal to you as would the look of everything around you.

Second scenario, speed of light.

You, the plane and the person sitting ten rows back would be converted into energy. No speech no hearing.

Second scenario (b), just below the speed of light.

Because you are in a plane you are in a fairly sealed environment. The air around you is traveling roughly at the same speed you are traveling. As such, all sound and speech within the plane would appear normal to you. Things would look normal within the plane. Outside the plane, everything would seem to be speeding up compared to you (and the plane). By how much? Depends on how close to the speed of light you moving.