I don't think it is a toy noise after all I think I have realised what it is now ( or maybe not)
Liseth makes this noise mostly when I cover her house at bedtime. It is white with flowers on, which she loves to look at. Last night I was going to change to a new cover , she was pushing the new one off and shouting at me. I returned her usual one and she immediately calmed down, looked at her flowers and made her noise.