I have a son that started screeching and I would tell him to talk nice or sing and I would give him an example... a a a a, la la la, ma ma ma... or even just blowing bubbles.... distract her from the screeching and teach her something that you can handle... She is finding she has a voice at this age and you can help her by teaching her the pleasant sounds... She wants to communicate and she needs to. I wouldn't ignore it, it is a great opportunity for you as a parent to teach her, if she isn't saying ahahahahahah... bababab... dadadada... these are usually the first sounds they will start with my 1st son as we worked with him would go on for ever saying mamamamamamamama, it was sweet to listen to compared to screeching...
If you want to try something fun to help her communicate with you in, try sign language- We used a set of three DVD called signing times (play time signs and everyday signs) It is a large set but we only used the first three in the series because it was the communication we needed- They teach eat, milk, more, ball.... it was great we used the first video until they were over 1 and then introduced the other two.... By the time our sons were 6 months they could tell us they were hungry, wanted milk, or more... it was really fun to be able to communicate with them before they could talk.