The Phonetic approach involves two (Auditory& Visual) modalities.
How confusing the sentence, "My dad paid uncle a penny," could be to a child like that. It could look like, "Wy paq daip cunle a deuuy," or fifty or more other possible combinations.
The second is the Phonetic Approach to reading. This is commonly called Phonics, and uses two modalities in the reading task--the Visual and the Auditory modalities.
It is a process that involves decoding a symbol system of a symbol system.
The second symbol system is the grapheme (letter) on a page. This requires the processes of the Visual modality.
The first symbol system is the phoneme (a sound unit of the language). This activates the Auditory processes as the letters are sounded out.
The Phonetic approach has some advantages. Unfamiliar words can often be sounded out. Letters associated with a sound may be more easily distinguished.