Consciousness can be defined many ways of course and that's part of the problem I realize. I use it and think of it along the lines of wakefulness or being aware and present in the moment (what animals seem to experience) and then that added step where language is involved. It's more than language but language describes it pretty well. That added "language" step is what I'm calling "consciousness".
Spoken and written language is useful because it slows the brain down enough for ego consciousness to appear. Spoken and written language is processed in the left side of the brain, with the left sided of the brain processing data in a differential way. The uniqueness of the ego stems from the differential left brain. Like in calculus, differentiation finds the slope of a curve at a given point; unique.
Say we placed a cat with a hat. on a table, and then assembled people from all over the world, who spoke all the different languages on earth; about 7000 languages. Each language may have slightly different sounds or words to represent the cat with the hat. Each of these language sound sequences are differential and subjective. There is no universal set of words common to all languages.
On the other hand, at the level of visual input (see the cat with the hat) all 7000 people will see the exact same thing. This is what allows them to say their cultural sounds as a representation. This visual language of reflected light waves is universally objective, while the spoken language based on sound waves is subjective to each culture.
The spoken language is needed by the ego, but not by the inner self. The inner self is more right brained, which is integral or spatial and uses the 3-D visual language common to all. The inner self also uses other 3-D languages attached to the feelings and sensations common to human nature that defines us as a species. We do not need a word of love to feel love. The word came second with each of the 7000 languages having their own sound association.
The visual language, used by the inner self is a much faster language than the spoken or written language. One can see a complex event in a second, which may take many pages of text to describe. This higher speed is not easy to transfer to others, unless we slow visual language with a spoken language representation. If we don't need to transfer the visual language to another, we can use it full speed.
For example, the batter hitting the baseball, makes use of hand eye coordination. There is not enough time to break down a fraction of a second with language and still hit the ball. Rather the ego will by-pass audio language in favor of pure visual. It may slow it down after the ball is hit to coach the child. Subliminal programming picks up very dense data, with the density making it below the threshold of audio language unless you ponder it long enough to slow it down.
Spoken language is more designed for social interaction via the ego. The super ego of culture (cultural rules and knowledge) takes the place of the inner self; outer self of culture. Self awareness makes use of the audio language to translate the visual and sensation languages of the inner self; symbols. One will slow these fast spatial signals, fluffing these with spoken language, like popcorn, so it is easier to digest. This is often too hard so people assume it not there and only hear the outer voice.