The written word is a visual representation of an auditory projection. The abstractions of written language allow for the description of a visual representation, ie. 'an orange ball'. As such the two senses are at least minimally close loop connected in that each can be transposed to the other. Of course there are other senses in addition to visual and auditory, foremost taste, touch and smell - amongst others such as spacial orientation(balance) or proprioception(location). For humans these other senses have a disparate bandwidth with regard to the visual or auditory senses. braille represents the ability to go from the visual word to the tactile word, but only at the simplest abstraction of touch. In fact the written word does not typically use more than meanest perception of sight, a 2D orientation with a binary contrast is all that is used to represent the entire scope of the auditory word. No general purpose effort is made to use our remaining faculties of sight (depth and color) to enhance the written language. The same goes for braille, a straight forward 2D array of contrasting points is all that is used and makes no use of any other tactile sensation such as warmth.

It might be interesting to map additional auditory information on to the remaining visual components, something like mapping pitch to color and duration to depth, or the like. Going beyond that, one might make a complete sensory translation matrix to map one sense on to another. If nothing else this would provide a common reference for people to describe the relative degrees of sensory perception that are now only vague and subjective.