Daughter refusing to speak normally

oh don't be ridiculous, autism isn't a get out of jail free card for normal childish misbehaviour. Sometimes the behaviour is just them being naughty/childish/silly and needs addressing as such.

And? Your daughter isn’t your nephews 🤷🏼‍♀️
I know several autistic kids who baby talk, it’s one of the most common signs between ages 7-12

I'm saying that your DD very much is neurodivergent

You know everyone can read exactly what you wrote?

i would not let it upset me that much. Fine, let her know you’re not impressed, but without getting irate or letting her know it upsets you. If her teacher won’t put up with it and her friends are getting sick of it, she might realise it’s not doing her any favours very soon.

It sounds annoying and probably a way to get attention. At first my advice was going to be not to make a big deal of it. Just casually say that she needs to speak in her normal voice for you to understand her.

However, it seems as though something potentially serious is going on with her. Why has she seen three psychiatrists?

Oh gosh it's almost certainly an annoying phase but I would totally call her bluff

"oh it's 6pm bedtime for baby girl"

"no juice for babies, only water"

"no sweets for babies"

no tv baby, it's bad for you whilst you're so little. Here's a book

and repeat with everything fun

my dd is ND and did this.

I treated it exactly like others here have advised.

Ignored it, or told her that i don't speak baby speak, and if she wants to talk to me, she can ask me properly.. then stuck to my guns.

She soon stopped it.

Is anybody,ever " typical"
Its madness!
The OP sounds like a sane , rational, boudaried person and the daughter is being rather annoying. Nobody has a syndrome here. The OP says so.
Some good advice re ignore and praise age appropriate conversations.
Hang on in there OP.

@BippityBopper Nobody has diagnosed anybody. Read my posts again. I said “it sounds like” & I made it very clear that my ONLY reason for saying so, was that my autistic child does the exact same behaviour.
Even if I had ‘diagnosed’ I’d say what is far worse, is all the posters on here, telling OP how she should punish this child who very well could be autistic. It’s disgusting

What is the situation with her friends, you briefly mentioned they don’t want to spend time with her any more because of this, how exactly has that come about? Have they/their parents openly declined invitations to socialise purely because of the baby voice thing? Is she aware of this? Is she not bothered?

When I was around that age I used to talk in an American accent (there are some cringey old vhs tapes that I hope never see light of day again!) but it was just a bit of fun, and if my mum told me my friends didn’t want to see me any more because of this I would’ve stopped straight away.

You know it"s a you problem but you punish her anyway?

I'll also say mine had same thing with her little friendship group doing it and their mums came down hard too, it's so infuriating!

I'd tell her the other children will be making fun of her if she does it at school so it would be best to stop it now as the habit will be hard to break. Then I'd ignore it, no feed it with attention. Kids can be so annoying at times, good job we love them.

I hope you don't have any kids. If you do, I feel so sorry for them if you can think this way.

Ah mine does this and it absolutely drives me insane. I have sternly told her I will not be ignoring when she does it. And when that doesn't work punishments came in when on holiday. iPad went away for a day for example. I've explained she can do it when playing pretend but not real life. It absolutely flips a switch of rage in my though, very hard to not go in really harsh but know it's a me problem not a her problem so I do keep level but it really pushes my buttons. Mines 7, I really hope it doesn't carry on to 8 like yours!!! You have my upmost sympathy

There must be something else going on for her to have seen three psychiatrists. Someone must be very worried about her to keep referring her to them.

Sorry if this has already been asked or answered somewhere - but have you asked her why she is doing it? Not in an aggressive or chastising way, but in a genuinely curious way. Id be interested to hear what she said!

I suspect it’s just a phase. As others have said, I’d just explain to her that you won’t be answering her when she talks like that and she needs to expect her friends won’t put up with it when she’s in school and leave it at that.

I'm sure I've read somewhere before that they do this when they need to be babied a little, or need more attention. Sometimes we can expect young children to grow up way too fast. I'm not saying treat her like a baby but I would spend time playing, cuddles, lots of one to one time for reassurance.

I'm not sure that six weeks off is good for either children or parents.

Not for the parents who choose to have them; Children, however, are fine and need the time off from being trained robots.

You what? I hope you're joking (in a very unfunny way).

It would annoy the hell out of me too but I would be communicating that. If my kids prolonged anything like this to the point of annoyance they would get grey rock or a telling off. Beyond that I’d be explaining how silly they will appear to all their friends.

I wonder if she picks up on the fact that you’re overwhelmed and emotionally upset by it? There could be an element of her enjoying the control she has over you, which, at this age needs to be nipped in the bud by a change in your attitude to one of parental tough love rather than locking yourself away.