How do you say "I hear you"?

Question

How do you say "I hear you" meaning "to sympathize with; to understand the feelings or opinion of" (Wiktionary; see also tFD, Macmillan, ELU, Urban). Do you need a (preposition and a) pronoun, some complement or just a verb and which verb is that (comprendre, entendre, sympathiser)? Do you say something different if it's used "as a prelude to disagreeing with what has been said" (third example)? Take for instance the following examples:

You're tired of all the ads on TV? I hear ya.
I hear you, honey. I know you're in a lot of pain right now.
I hear you, but we just can't afford to make any big changes like that at this time.
I hear what you are saying about the strength of feeling on this issue.

Answer 1

There is a French equivalent when used to acknowledge your interlocutor's point of view, but it is rather formal: j'entends bien.

J'entends bien, mais nous devons faire des économies.

More common phrases may be, depending on the context:

Je sais

Je sais bien

Je comprends

J'ai compris

j'ai bien compris

Je suis d'accord

Je suis bien d'accord

They can all be used as a prelude to a counter-argument in a discussion.

Je sais bien, mais on ne peut pas se permettre de tels changements pour l'instant

If you want to express a sense of sympathy, after a rhetorical question, as in your first example, a more appropriate turn is comme je te comprends:

Tu en as marre des publicités ? Comme je te comprends.

Answer 2

There is a verb that precisely means "to sympathize with; to understand the feelings or opinion of", although sligthly formal, compatir :

Je compatis.