[latebind (OP)]

Would sound travel at the same speed on a planet with a different atmosphere to earth, like Venus or Jupiter?

[daveshorts]

Simple answer is no, the speed of sound is very dependent on the material it is travelling through. It changes on earth with the temperature of the air, so the speed of sound where jets fly is more than 10% lower than at ground level. If you are under water the speed of sound is about 1450m/s - 5 times faster than in air in rock it is about 5km/s and in diamond about 12km/s.

In gasses the speed of sound is proportional to the square root of Temperature / molecular mass and is also dependent on the gas's specific heat capacity.

So finding anywhere with the same speed of sound as earth would be pretty good going