HOW DO YOU CALM A VIOLENT TEEN???

As others have said, this sounds like a sensory issue.  If you don't experience it yourself, it is really impossible to understand just how awful it can be, and I doubt that the daughter who shares a room with your autistic teen understands.  It sounds as though both of them view the other's opinions as unreasonable.

I cannot stress enough how awful it is when you are met with an all out sensory assault.  You can see from the extreme reactions from a few people responding just some indication of how unpleasant it can be for those on the autistic spectrum.  This is something that your autistic teen's siblings need to understand and be more thoughtful of, though given their likely ages I think it is probably not always going to work out the way you and I might hope.

The kind of outburst that you describe is a sign of desperation because of a situation that for her is extremely unpleasant, and which she has found herself unable to escape.  You can avoid it happening if you can avoid the conflict that causes it and give her a safe place to retreat to.  This will require greater understanding from her siblings to be really successful.

To give her the best chance of coping, I suggest defining a safe space that is just for your autistic teen.  I had something like this that I created in my parents' home when I was a teen.  It was just an area that has curtains around it, attached to furniture, so I could close out the light.  Everyone knew to stay quiet around it, although admittedly younger siblings were not always understanding.  Perhaps curtains around her bed?  Along with rules like "do not spray things in the bedroom" and having defined places where making is noises is acceptable (e.g. living room and kitchen), that do not include the bedroom, I think this could really help.

I think better education of your autistic teen's siblings would really help, along with creating a safe space.  Ideally she would have her own room, and that would be the safe place, but that cannot always happen and so thick curtains that block the light and give her less visual stimuli would really help her to cope.

Unfortunately, where experiences differ so much, it is extremely hard for either to empathise with the other.  Teenagers also, with their raging hormones and mood swings, tend to like to antagonise one another, and your autistic teen will always be worse off in these situations.  I hope you can persuade them to be more tolerant of their sister.

As others have said, this sounds like a sensory issue.  If you don't experience it yourself, it is really impossible to understand just how awful it can be, and I doubt that the daughter who shares a room with your autistic teen understands.  It sounds as though both of them view the other's opinions as unreasonable.

I cannot stress enough how awful it is when you are met with an all out sensory assault.  You can see from the extreme reactions from a few people responding just some indication of how unpleasant it can be for those on the autistic spectrum.  This is something that your autistic teen's siblings need to understand and be more thoughtful of, though given their likely ages I think it is probably not always going to work out the way you and I might hope.

The kind of outburst that you describe is a sign of desperation because of a situation that for her is extremely unpleasant, and which she has found herself unable to escape.  You can avoid it happening if you can avoid the conflict that causes it and give her a safe place to retreat to.  This will require greater understanding from her siblings to be really successful.

To give her the best chance of coping, I suggest defining a safe space that is just for your autistic teen.  I had something like this that I created in my parents' home when I was a teen.  It was just an area that has curtains around it, attached to furniture, so I could close out the light.  Everyone knew to stay quiet around it, although admittedly younger siblings were not always understanding.  Perhaps curtains around her bed?  Along with rules like "do not spray things in the bedroom" and having defined places where making is noises is acceptable (e.g. living room and kitchen), that do not include the bedroom, I think this could really help.

I think better education of your autistic teen's siblings would really help, along with creating a safe space.  Ideally she would have her own room, and that would be the safe place, but that cannot always happen and so thick curtains that block the light and give her less visual stimuli would really help her to cope.

Unfortunately, where experiences differ so much, it is extremely hard for either to empathise with the other.  Teenagers also, with their raging hormones and mood swings, tend to like to antagonise one another, and your autistic teen will always be worse off in these situations.  I hope you can persuade them to be more tolerant of their sister.