Notification Symbol meaning in Jellybean System icon that looks like ear with line through it on JellyBean

I'm Using Sony Xperia P with Android 4.1.2. Can anyone tell what's this icon (one with small T) to the left of battery bar.

![enter image description here][1]

Using Sony Xperia P with Android 4.1.2 .? Is it any application based? [1]: https://i.sstatic.net/XDntV.jpg

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Tweeted twitter.com/#!/StackAndroid/status/464971524835790849

occurred May 10, 2014 at 3:33

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asked May 9, 2014 at 20:28

Notification Symbol meaning in Jellybean

Can anyone tell what's this icon (one with small T) to the left of battery bar.

![enter image description here][1]

Using Sony Xperia P with Android 4.1.2 . Is it any application based? [1]: https://i.sstatic.net/XDntV.jpg