That's the noise the gently rocking pressure regulator on the top of my pressure canner. When I can beans, they are processed for 1 hour and 30 minutes at 10 lbs of pressure, and that pressure regulator makes the shushing sound for the entire time. Every so often I check on the canner, just to make sure we're still at the right pressure.
I would like to say that canning dried beans like pinto and black turtle beans is easy--and it is in the sense that none of its steps are hard to understand. But it's not in the sense that it's time consuming and there are quite a few steps.
But it's so worth it. While canning tomato soup and salsa is fun for me--I distinguish between the two products. The soup is an actual meal. For every quart of tomato soup on the shelf, that's one meal I don't have to buy more groceries for.
Well the beans are the same way. Last year I bought about a hundred pounds combined of pinto and black beans. To my great delight, pressure canning the beans allowed me to add in some flavor (seasonings and some chopped onions) and get a better, smoother bean product at the other end. I almost always puree the beans straight out of the jar and then into a pan on the stove to reheat for burritos or quesadillas. I use the beans whole to add to chili or soups. Today I used a jar to make a corn and black bean salad which is just . . . yummy! Besides the fact that the taste is great--it cuts the preparation time at the other end to 5 minutes tops. And that keeps us from buying expensive frozen convenience foods that aren't good for us and are a waste of our snug grocery budget.