Excuse my virginity in linguistics, but it seems to me that phonetic alphabets are "only" protocols for audio compression into visual input/output media, optimized for human throat sounds.
I suppose that when a person gets a letter or word through visual input, her image recognition cortex sends virtual audio to her auditory cortex and only then she transforms these sounds into abstract concepts.
I suppose that this works in such an inefficient way because speech was invented long before writing, and early writing functioned as audio recordings of speech. Evolution often makes such inefficient systems, having to improvise "on the go".
So, my question is: does auditory cortex participate in reading process when human reads non-phonetic hieroglyphs? Or in this case hieroglyphic visual input bypasses the auditory cortex and transforms directly into abstract concepts?