Of all the incredible tales from the book Arabian Nights, the one that I still remember is the story of Ali Baba and the Forty Thieves. In the story, Ali Baba is a wood cutter who discovers the secret voice password “open sesame” that opens the door to the thieves’ den. This makes you think if we can also create voice passwords for our devices and lock or unlock them just by speaking the password to the devices. At least in Android, it has become possible through the free Voice Lock Screen app. This app allows you to set a secret phrase as your password and unlocks the device only when you speak the correct phrase.
In the Voice Lock Screen app, you can choose a lock pass phrase that you must speak in order to unlock your device. But if you somehow forget to remember the correct pass phrase or are not able to speak it correctly, then the app offers an alternate way to unlock the device by touching the sound waveform. If you think that waveform touch unlock feature pauses a security problem (anyone can unlock the device by touching the sound waveform animation), then you can also disable it.
There are various other settings to change the lock screen look, for example, you can change the color and size for the time and date displayed on the lock screen. When you are done with all the settings, then you can touch on the ON button (lower-right corner) to enable the Voice Lock Screen for your Android device. Now when you lock your phone, you will have to speak the password before you can unlock your phone.
Conclusion: The Voice Lock Screen app can add a interesting feature that allows you to unlock your Android device by speaking the pass phrase. But since the password is being spoken aloud, it is not really very secure way of protecting your device.
You can get the Voice Lock Screen app from https://play.google.com/store/apps/details?id=cx.makaveli.voicelockscreenhd.