According to the patent, apparently this is predicated on the idea that all our ears are uniquely shaped, thanks to the various ridges and folds that form our ear. This means that it is very unlikely that your ear could be shaped similar to someone else’s, thus making ear unlocking an interesting and possible feature.
It could also offer up a more efficient way of protecting your phone. At the moment regardless of security, anyone can answer a call on your phone. However with ear unlocking, the phone could remain locked until it is held up against the ear of the owner in which it will then unlock and answer the call at the same time.
That being said the feature could be rather annoying as having to lift our phones to our head can be cumbersome. However it is possible that ear unlocking could be limited to answering calls while more conventional unlocking methods could be used for the rest of the time. Of course given that this is a patent there’s really no telling if and when Amazon might actually implement it.