I must admit, sometimes it's great and highly productive to work in absolute quiet, especially when I have a lot to do and a little time to do it in. But finding that kind of quiet is rare when you work with and around people. People make noise, just by breathing (sidenote: heavy breathing when all you are doing is sitting at a desk kills me).
Why must others change their work behavior to fit your need for quiet? That is a truly unrealistic expectation, or even desire. Don't be 'that' co-worker, supervisor, or business owner; we all have to take our peace into your own hands. No one else is responsible for your comfort, you have to be comfortable within yourself before you will ever be able to truly appreciate the talent, skill, drive, and hustle around you. For some that peace is obtained through meditation, prayer, exercise, or simply noise cancelling headphones. I like to put on headphones and actually listen to music to drowned out the sounds that I don't want to hear. It calms my nerves in a way that nothing else does. For me, music heals all!
It just comes off pushy when you think that everybody else needs to stop talking, typing, breathing, or whatever loudly (in your opinion) just so you can do your job. If your job doesn't actually involve you listening for something specific total silence when you work around others is truly NOT GOING TO HAPPEN. You may want to come off assertive, but who ever desires to be pushy. Take the first step at achieving peace within and productiveness; it's in your own hands!