You would not be alone in thinking that our Bluetooth headsets, paired to our smartphones, already fit that niche. To a point, you are correct, but direct interaction with the smartphone is required to get anything channeled to your earpiece, be it music or navigation.
Think of something a little more autonomous, like in the movie Her. Embedded in this creation by Kazuhiro Taniguchi of Hiroshima City University, is a device that has a compass, barometer, speaker, microphone, gyro-sensors and GPS. It is called Ear Switch.
In the concept video below, it takes on a role of an augmented audio reality of sorts. The device is meant to be interactive too. It will be able to pick up subtle inputs from the user by how he or she opens their mouth. Tied together with head movements, the combination of commands can provide traffic information, point-of-interest information or directions.
So much of the content we deal with in mobile is visually related, but the Ear Switch has a form factor that is discrete. Mr. Taniguchi showcased the device at a business fair this past January. He is hoping to team up with a major manufacturer to bring this device to market sometime in 2015.