I'm taking French lessons. Despite the famous Académie française working to maintain the language with intellectual rigor, French has the most screwed up spelling of any language I know other than English. All these extra letters that you just don't pronounce. Or do you?

The basic rule with French is you don't pronounce the last letter. Paris is pronounced pair-ree, no s. Vieux is pronounced vyoo, no x. Vous is voo. Etc. Sometimes you have to skip multiple letters; ils parlent, for instance, is pronounced identically to il parle, roughly eel parl.

But those hidden unpronounced letters are in the mind of every French child, even if they don't usually use them. Particularly because of liason where the lazy French tongue sticks consonants in things. Vous parlez has no s sound but vous avez does (vooz-avey) to avoid having two vowels in a row. The liason rules seem relatively simple and phonological, but they do require you to learn the "extra letters" even if you don't often need them.

Things take a turn for the weird with pronoun agreement. There the "extra letters" sometimes play a role for grammatical reasons, not phonological.

Je le leur ai donné
Je la leur ai donnée

Both mean "I gave it to them"; the difference is whether the "it" is a feminine noun or a masculine noun. There's an e at the end of donné in the feminine sentence so the verb agrees with the pronoun. But you don't pronounce that e, so you can happily ignore it in spoken French.

Except, there are a few verbs where the pronomial ending does change pronounciation.

Je le leur ai offert
Je la leur ai offerte

In the first sentence offert is prounounced oh-fair, without the t. Second sentence? oh-fairt. So not only do you have to remember that the participle is spelled with a generally-silent t, you have to remember that the feminine pronoun requires an e on the end of the participle, thereby making the t pronounced.

It seems very odd that the grammar is dictating pronounciation, not just phonology. My teacher tells me French native speakers get this rule wrong all the time; I'm sure I will too. But it sure is fascinating.