Due to hit a crowdfunding site later this year, Hushme can be worn as a standard neckband-style wireless headphone -- it has integrated ear buds -- or in "masking" mode, which allows you to muffle your conversations.
As an added bonus, when you're in masking mode, the headphones tie into a free app that allows you to overlay masking sounds onto your voice. These masking sounds, which are output through an external speaker on the outside of the headphone, include wind, rain, monkey and squirrel, as well as Darth Vader, R2D2 and Minion. There might be some licensing issues with a few of those sounds, but the demo I got was pretty wacky (only one of the two prototypes was working, however).
Although the company is based in the US, the engineers behind Hushme are Ukrainian. As I said, Hushme is planning a crowdfunding campaign later this year and expects the headphones to be priced at less than $200.
You can use the headphones on the go, but their biggest market is probably for all those folks in open-office environments who are looking for some on-demand privacy. Hushme might also make a good present for that annoying co-worker with the loud voice who doesn't mind having everyone hear his or her calls.