Intelligent life is an inevitable consequence of the cosmos. We can not say with certainty that there exists other life out there, however it is equally incorrect to say that there isn't. I posit that we have not seen nor heard of extraterrestrial life because we do not see nor hear things in a manner that would make sense for a species with the ability to conduct intergalactic travel to see or hear things. As of now, our communication is limited to the speed of light, and speed of light is too slow to traverse the universe in a timely manner. Therefor, a species with intergalactic traveling abilities would have to have faster communication methods, and would exclusively use these methods, as they would have advanced past the point of needing to study the universe via light.