I'm curious: What does your "inner voice" sound like, to you?

[MTL]

It would be fascinating to know if other animals that use "language" are capable of thinking in their animal "voices"
especially if they are animals know for problem-solving abilities,
like dolphins, chimps, border collies, or magpies.

Obviously they are capable of thought and communication, like us,
but do they have the ability to "mentally vocalize", as we do?

And if Yes, do they ever do so?

And if Yes...what purpose does it serve?

My dog growls and barks in her sleep in between chasing and running .. all in a very sleep-restrained way of course.  But it doesn't look as though any animal uses symbolic language except ourselves .. though some are capable of learning parts of it.  I think they are capable of realizing a great deal, but unlike us I don't believe they create a symbolic substitute for the world the way we do with language.  Like them, we have perfectly good pre-human brains and I'm convinced we are as capable as they to move through the world purposefully and effectively without ever narrating our progress to ourselves.  The trick is to save the language for what it does well, convey ideas to other humans.  So, no, I don't think any other animal misapplies symbolic language internally because none of them uses it at all.

mmh....I'm not so sure about that, WTW.

We already know that thousands of species communicate with each other using different vocal sounds,
and some on a surprisingly sophisticated level;

like dolphins, primates, birds;
and they've been demonstrated to be capable of clear communication via symbolism,
although I acknowledge that there doesn't yet seem to be any evidence that any species other than humans
would naturally or spontaneously choose to employ such a device.

But I don't think symbols or hieroglyphics or the written word is necessary
to demonstrate that symbolic language is used;

many Native Americans didn't employ the written word at all,
their history was purely oral; passed along with each generation.

If we can dream about people talking to us,
and your dog can bark in her sleep,

...why not?