At nine months, behavior like you describe gets worse the more attention you give to it.

Example: Throwing food at dinner time and everyone laughs, the more they'll do it.

Throw her toy or bottle down, just to see you pick it up - over and over and over.

The best thing to do is to give it no reaction, and she will eventually bore of the game - it is a game to her to see what kind of reaction she gets.

They like to hear themselves shrieking. It's a way that they entertain themselves.

I agree with ignoring it, it will pass. You cannot do anything to stop it.

It's short lived.

I remember at that age, DD got into coughing. When she would cough like a cat hacking up a hairball people in the room would all turn around, and she liked the attention so much, she kept it up until we "ignored it out of her" LOL

My daughter did the screaming thing about 5 times around 9 or 10 months. When I would tell her to stop whe just laughed and screeched again. One time she screamed and I put my face close to hers and screamed back with an angry face and then said NO! I think I had to do that 3 times and she stopped.
Linda C

My children were not allowed to scream for amusement. They were given stern verbal admonishment once or twice and mom's cross face. If it happened in the car while I was driving, I would pull the car to the curb in an instant and sit until things were quiet. If that didn't work, mommy took a time out.

My grandson, 9 months now, gives those joyous yelps, he'll do it while he's babbling and when he's excited. We love it and he's so funny. He especially loves to do it when he's sitting with his Dad or Uncle Dave and they are trying to watch CNN!

He also loves dropping things so we can pick them up, so he can drop them again. When we tire of the game and don't pick up what he has dropped, he stops doing it (until the next time).

It's just a pre-talking phase, she'll move on to other noises soon.

Enjoy

My kids didn't do this at that young an age. I've noticed it more in older toddlers. I don't think there is much one can or should do to correct an infant that young except ignore the behavior.

Distraction works well and I agree that you should ignore the sound, then she will eventually stop.

A bit annoying when out in the car....that could give you a fright and distract you, so I guess it is rather dangerous.

Doing it back to her might help, then she would know what it sounds like and hopefully how annoying it is.

Enjoy your lovely GD.

Popi

They don't know what is socially acceptable and what isn't. What hurts an adult's ears is a musical masterpiece to an infant or toddler. While screaming back might scare it out of them, I think the imitation is more likely to reward and reinforce the behavior. As they say, imitation... form of flattery. It also doesn't meet the goal to model socially acceptable behavior.

I would ignore and distract with a calmer, more fun, sound that I did want her to imitate. When she learns better ways to communicate she won't need to scream anymore and will outgrow it.

Another thought is she might do it to relieve pent up energy, excitement or stress. I taught my kids to blow really hard and eventually to count when they were angry. You physically cannot scream or cry and blow at the same time. I hold my finger out and pretent to blow it over (like a candle) and get them to imitate me. It's quiet and settles them down by distracting them, and making them focus, take deep breaths, and sometimes gets them giggling. 9 months might be too young for her to understand that, but it's something to try when in the next few months the shouting is out of frustration and temper.