Google Thinks It Can Replace Passwords With Inaudible Sounds Only Your Phone Can Hear:

Google has acquired SlickLogin, an Israeli startup that has developed an ingenious solution to the pain-in-the-butt that is "two-factor authentication" (when you have to Punch in your password and a code from a text message on your phone to access a web site or app).

The company lets your phone "listen" to a web site, and the confirmation of the unique inaudible sound confirms it's you trying to get access, not a hacker in a remote location.

You'd never need a password again just hold your phone near your computer.

Cult of Android explains it best:

Here’s how SlickLogin works. You visit a site that supports SlickLogin. Instead of entering a name or password, you simply hold your smartphone close to the laptop or computer you’re using, and entry is granted.

What’s really happening is that the web site is playing a sound, which is encrypted data encoded into ultra-sonic (higher than human hearing) sound. Your phone hears it, and sends the data back to the SlickLogin servers. That’s the authentication.

The sound code is different each time, so person requesting access has to be in the room every time — hackers can't do that.
---------------------------------------------------------
But i ( J.E ) think it's best option for Hackers to get easily into someone's account/System because a Hacker can generate these sounds in a single task!