why do so many speak with an interrogative lilt at the end of their sentences?

It is mildly irritating. I think it is an attention getting device. People do it who are used to being ignored. Asking a question often gets an answer, the listener's ears perk up. That is why it is annoying because you perk your ears up for nothing.

Too funny..

Now that you mentioned it.... Actually, I have noticed a fad of mostly women who if asked a question will answer with a affirmative of; Example: "I will, or I do, etc. etc." The tone of voice is much higher. It is annoying and believe me I will never add this to my way of speaking... Its a fad and as soon as every "Step ford" wife,Movie Star, College kid, and the Copycats,,,,figure out they are parroting each other in this new habit of speach, it too will end!!!!!!!Hurray hurray.. At first I thought it was cute.. really sweet... (barf) but then when I heard several actors (men and women) on the late night talk shows all speaking in the same tone and two word answers, I realized that there was an epidemic out there...

How stupid is that? It seems to have stopped some .. oh well.

I think TomK is entirely correct. They're afraid to make statements and take a stand on "this is what I say". It's the same reason they end all typing with lol, haha, etc.

It's VERY annoying. Even my mother is starting to speak that way. She has a lot of "y'know?"s and "like"s, but is just starting the upward lilt. It's especially bad because she's in her late 50s!

I must say this is a very Australian thing.

I don't hear this in the UK much. I do think is a bit irritating mostly because I can't tell if its a question or not. I guess its not the same if you are Australian.

It's not normal to make everything sound like a question.

It is a sign of doubt and insecurity and is done by people seeking approval. They are afraid to make a statement, so turn it into a question and thereby put the responsibility on the responder.

Speech idioms are learned, copied and then become part of everyday speech with some people. Once people mature, language will mature with experience and need. Hopefully.

My friend does that all the time and it's really annoying! She raises her voice at the last word of every statement! I imitate her sometimes to make her stop, but she doesn't take the hint...

Its totally, like, y'know, a teenage girl thing(?), which, like, y'know, totally became more and more, like, prevalent(?). Now it totally seems, y'know, like everybody, like, talks this way(?). Y'know?

yes? lol

your pic is ugly