City dwellers on their morning commute might like to drown out the world with a pair of noise-cancelling headphones, but some noises, like someone calling your name, are better off not cancelled. Amazon has been awarded a patent for headphones that can recognize specific keywords, like the wearer's name, and temporarily shut off the noise cancellation to prevent accidental friend-snubbing.

As opposed to passive noise-cancelling – basically just soundproofing – active noise-cancelling devices create their blissful bubble of peace by listening to the sounds of the outside world and generating a negative waveform of the incoming sound that is then mixed with whatever audio the user is listening to.

The problem is, these devices don't differentiate between noises, so the headphones will cancel unwanted noise, like general street rumblings, along with important things like people calling your name. Amazon's patent filing describes a device that lets users single out a specific word or phrase, and when it hears those keywords, it can either suspend the noise-cancelling functions, or generate that sound through the headphones. Users can then resume the noise-cancellation with a voice command or a button press.

Over time, the device is designed to get better at weeding out false-positives, too. If a user always turns the noise-cancelling back on immediately, the system can learn to be less sensitive. It can even be set to only recognize the chosen phrase when it's spoken by a specific person – so the boss saying "Hey Ben, lunch time" gets through, while still filtering out coworkers constantly saying "Hey Ben" just to mess with your headphones.

Of course, being patented doesn't necessarily mean the idea will show up in any retail products soon, but it does show that the idea is on the table.