Unnoticeable
Part of speech: adjective
Definition: Not noticeable
Insignificant
Part of speech: adjective
Definition: Not significant; not important, consequential, or having a noticeable effect.
Example sentence: The relation between a poet and audience is really insignificant. What matters is the poet is hearing something that he is broadcasting. And whether there is anybody with a receiver isn't the reason he does it. He hopes there is somebody receiving it.