Oh, so you're a teacher. Which school are you teaching in?plus what subject? Haha be glad you don't have me as a student as I'm super straightforward and sarcastic, but fret not, my form teacher is exactly like me so no trouble( birds of the same feather, flock together)
Yehet, I've a variety of teachers from freaking awesome ones to those who you wonder how the hell did they pass evaluation. It depends really, my A math teacher just stares and it somehow keeps the class quiet, same for chem. Yeah and they give breaks to maintain the class' s attention :)

I'm not a teacher but I have a HORRID teacher that can't teach.
To get them to pay attention, make the class interesting. Getting frusterated is ok but if you get mad, most likely, the class will laugh at you. Try to make the class fun to listen to, and get the classes attention by sometimes talking about what they want to talk about. Sometimes the easiest way to get a class to listen to you is to be the mean teacher that nobody wants, but that comes with people talking bad about you and no student wanting you as their teacher.
Try to think this way:
Don't feel bad for yourself that the students aren't listening, feel bad for the students who are going to fail because they aren't listening.

I also don't recommend changing the seating plan, my bad teacher once did this and students were yelling across the room, and some were being total idiots and were sneaking back to their old seats. Also be ORGANIZED, if students believe that you're not organzied then, they wont bother to pay attention because "It's a waste of time"
What class are you teaching?

I'm not a teacher but the other way around. I am a student and I tell you a very naughty one. Teacher always do this to shut me up. Stop from what they doing and ask me what they just teach. The other student will stop talking and look at me. The second way is a bit cruel but affective. They give me warning first then if I don't stop, I got my detention. Everyone knows student hate detention including me. If you have any question, you can ask me. I will answer it for you.

I'm not a teacher, but I used to be our school's librarian. If you want them to shut up, give them stares and hints them that you're cool as long as they don't give you s. stare always worked :D

If your students are noisy, try to catch their attention one time. If they don't pay attention, try to get their attention by hitting something like the table or the board. It's okay to get angry. If they don't stop, call their attention by making them all stand up. Don't scold them, but instead, try to make a consensus out of them, like for example, if you are having classes and they are noisy, assign someone who would write down the names of those who are noisy and agree on a punishment with them. If that doesn't work, give them pop quizzes every single time they aren't paying attention. Another good thing is to give "good noodle" like gold stars for each student who would behave well or do good in class. Agree to a point system with them...wait..are they kids? this is applicable for kids ehehehehe..i hope this helps

Are they talking because they don't have an activity to do? Having well-structured activities with set time limits really helps with the noise level.

If they're talking while you're talking, stop and stare at the noisy kids. After a few moments, some of the other kids should notice and bring it to their attention. Once they stop talking, thank them and keep on teaching.

I could give you other suggestions if you tell me more details. :)