I use them while I work. I work in an office setting and most people here wear them. I will leave one out in case someone walks up needing to talk.
I wear min all the time. I work in an open office without cubicle dividers. Lots of random noise and talking. It lets everyone know I am getting s"@$ done and don't want to be bothered. Which is a majority of the time.
I work in a inbound customer service department. Meaning we have incoming calls from customers needing to order parts or whatever customer service requests they need. There are a lot of people that wear them for lots of reasons. At any given time there are about 25-30 different conversations going on and all that background noise gets to you after a while. It's nice to not have to hear other peoples conversations while you are not working with a customer at that moment. I've never really used them, but I will play music, or Youtube videos through my speakers when I'm not on the line with a customer. I have been considering using some buds so that I'm not noise polluting my coworkers. There are times during the day when we are very busy, but other times we are waiting on that next call to come in. Our department is pretty relaxed because we do a great job at servicing the customers in a timely fashion, and we are all grown up professionals so nobody really takes advantage.
I work from home and all of my communication is Email or IM based so Sports talk radio is usually on in the background or Pandora. As many have stated above its all about the job and what it requires. If I still worked in one of our infusion branches I would not use earbuds because I would need to deal with the clinical staff or other warehouse personnel to much communication can be lost when you have something plugged into your ear.
I could not imagine my work day if I wasn't allowed to have my earbuds in while working. For me it's a way to drown out the noisy people I work with who talk about their pets and vacations coming up as loud as they can. Only time I would not have them in is when im running equipment like cranes or hi-lo's
I work as a financial advisor. So I ho to my clients offices or use a boardroom so no earbuds then. When I'm at my desk I plug in to some good music and work uninterrupted. We don't allow clients upstairs.