I made the same mistake. Konnt ihr (with the umlaut) is present tense meaning "are you able to". Konnt ihr (with umlaut) also means "could you", but in the sense of a polite request. "Could you (please) listen to me in the back as well." But that would be a different verb, anhoren or zuhoren, I think.
Those are not nouns but pronouns. Pronouns are not capitalised except for the formal you (Sie) and its forms (including the possessive adjectives).
It is not to distinguish, it is capitalized as a form of paying respect, i believe. Even so, there are still many "sie" or "ihr" that are distinguished (in number and case) only by the grammatical context, like how the verb is conjugated. Here it is the plural 2nd person in the nominative case (it is the subject of the sentence, as you can recognize by the verb conjugation). So it is "you" as in "you guys can hear me?", but only the rest of the sentence can tell you that.
An equivalent in english is "her". can be an 'article' as in "her shoes" or the accusative/dative of the 3rd person singular, feminine in "i told her" for example. Only the understanding of the rest of the sentence can tell you which it is.
Hope i didn't make it worse :-/
Imagine a classroom or lecture hall. The person in the front is speaking, and asks if the people in the back (or rear) of the room can hear. Back is opposite of front. (But now you have me wondering why "come back" means "return"--you could walk from the front of the room to the back (rear), and then come back (return) to the front!)