Could alien signals be hidden in space noise?

Yes — alien signals could be hidden in space noise, and that is one of the main challenges in SETI.

A weak or distant signal could be masked by natural cosmic radio sources, distorted as it travels through interstellar plasma and gas, or buried under human-made radio interference from Earth and satellites. In principle, a technologically advanced civilization could also use transmission methods that make a signal harder to notice unless you know what to look for.

Astronomers search for narrowband tones, unusual pulses, repeating patterns, and other statistical anomalies in large radio datasets to separate possible artificial signals from ordinary background noise. They also increasingly use machine learning and other AI tools to help sift through huge volumes of data and flag unusual features that traditional methods might miss.

That said, there is no confirmed evidence of extraterrestrial signals so far, so this remains a possibility rather than something we know is happening.