Spirit speach

You can speak to the spirits, and most will have some understanding. But they don't communicate back like you and me. They are not usually physical, so making word sounds presents them difficulty.  And most will not understand written words at all.  Spirits speak in a soundless "spirit speech" that floats as images in the mind, images and feelings.

"Lore of the Naming Kinds" by Honored Loee#, taurien year 3533

Spirits communicate via projected thought and feeling.  They may learn spoken languages but typically sophonts learn to understand the projected spirit speech method of communication.  The Primitive Talent magician also may develop this mind to mind unspoken language, instinctually harnessing their own Po.  This may be just sensation of emotions and feeling or images and even projecting words as if spoken into the minds of others via a magic called "telepathy".  This projected word method requires the recipient understand the projected word sounds that they "hear" in their mind.
Scholars have found the spirit speech is shared amongst all spirits of nature, choruses and types. Even the malices and Banes use this method of communication and a form of it, more akin to telepathy, is used by ghosts in communication with each other. Of course ghosts also may manifest to speak normally. The body ghost or Po likewise communicates in it's basic ways via spirit speech.
Shamen, Taurien Glory Path, Primitive Talent magicians and Ghenid all have some capacity in spirit speech. The Ghenid is most limited in that it only functions with the ghosts they own by their magical bindings called Aedoteerua: The Soul Chain.  Ghenid are deaf to all other spirits.