Optical words, nouns, verbs, adjectives and graphic images are input commands to our eye/optical  computer system.
Audio spoken VERBAL words are input to our ear system.

Harmonic sound waves comprised of  music lyrics with instruments are input to our  ears.

Do we understand the input?  At the surface level, the obvious level,  we probably do.
Do you understand the subliminal mind tricks of television and radio  broadcasts? NO.

Please, pay  attention!