This is a very important issue with finding intelligent life elsewhere that I have been discussing in my article.
We have our own interpretation of life. We are carbon-based animals, and other lifeforms may be based on an entirely different chemical structure.
Therefore, we may fail to acknowledge their presence due to a vastly different body and chemical makeup.
As for communication, that’s another issue not usually considered. Even other animals on earth use a variety of communication methods that are very different from the way we humans communicate with speech. Whales, dolphins, and porpoises, for example, use a low frequency sound that travels through water to communicate with one another. Bats us sonar that bounces off objects so they can determine what is in their path.
With all that in mind, it may be very difficult to communicate, should we ever meet up with intelligent life in the universe.