In Old Town shortly after you arrive there will be a side quest that you pick up from the Ember Tower called Legless Spider. You will have to talk to a runner named spider and he will make you go fetch 3 items. Next to the South East item you will be stunned by sound waves, this is the screamer. Don't back away just go right for it and push
to interact.
I found this before the main quest where you have to go into the apartment complex that introduces you to them.