When Christ was challenged about the woman who had seven husbands, and whose wife she would be in heaven when she died, He replied there is no marriage but that we would be like the angels.
Since we will be like the angels, it stands to reason the saints will communicate like angels.
There's an article here on angelic communication.
catholicmagazine.news
Evidently, communication between angels is not expressed with sounds, gestures or other material elements, since their nature is solely spiritual. Communication is achieved by an act of the will, by which an angel directs a thought to others, giving them to understand concepts he already possesses.
Heaven will not have the physical requirements for speech. For a start there will be no air to transmit sounds.
That is not to say that angels can't manipulate our atmosphere for purposes of speech when it suits them. Gabriel spoke to Mary. Now either he was actually "speaking" or just going through the motions with the actual communication being spiritual, but appearing as speech to her.
I've often claimed the night my father died he appeared in my room. We talked and argued. His body was lying dead in a flat miles away, so he had no brain, no ears, no vocal apparaturs, no eyes. But it was obvious he could see, talk, hear and think.
Now was our communication actually physical, ie. did the air molecules vibrate, or was it spiritual with the appearance of being physical?
I don't know, but if it was the latter it went right down to the tone of his voice. I knew what he sounded like, having lived in the same house for the better part of 20 years altogether and he was "talking" in his usual voice, sans vocal apparatus.
I think we'll communicate directly, and possibly obtain "enlightenment" from suprerior angels as per the referenced article, and speak back to them directly by infused concepts, without language as angels do. Likewise we'll speak to God and He will enlighten us, although He may choose to do so through angelic beings rather than directly which could be a bit overwhelming, like trying to empty the Hoover Dam through a household tap.