Determinatives don't represent sounds, instead they imply meanings to phonetic (sound) characters and help eliminate confusion by putting the writings in proper context. These special characters clarify a statement by imparting a distinct meaning with their presence. The appearance of a determinative puts other writings in context.
Remember this puzzle?
It could have several possible meanings:
I Heart You
Eye Heart University
I Love You
The addition of another image might add some clarity. The determinative doesn't represent sound, but adds meaning. Take a look at the same puzzle with the addition of another character.
The baby cherub shooting an arrow is one depiction of Cupid, the Roman god of love. By shooting someone with his arrow, Cupid caused them to fall in love. Using of this symbol in this context might imply that the statement relates to matters of love and emotion, which would make “I Love You” the only choice.
In this case, the cupid character implies meaning but has no spoken sound. Hieroglyphs worked the same way. The hieroglyph could add meaning but was not spoken.Here are some examples of hieroglyphic determinatives:
All hieroglyphs that appear are included in the Horus-Advanced hieroglyphic font.