原来 Xperia T 是 HD Voice Certified，一个 GSMA 的认証！即是在一个嘈杂的环境下通话，你只要如常地说话，无需加大声量，对方也可以听得清清楚楚。
Xperia T is HD Voice certified*. This means that you can talk normally and be heard clearly, without having to raise your voice, even in noisy environments. Now you don’t have to shout to be heard. Or try to find a quiet place to listen. Got to hear it to believe it?
其实 HD Voice 不是新科技，之前已有一些手机支援，例如：Xperia Arc, Neo, Play 等，Nokia N8, C7 也支援的。不过，要用 HD Voice 也要通话双方和网络支援才可应用。
HD Voice connections depend on HD Voice support from both connected phones as well as the network. Please refer to your network provider for information on HD Voice support.
若有兴趣可以到 GSMA 网站聆听一下 HD Voice Sound Demo。
http://www.gsma.com/technicalprojects/hd-voice-sound-demonstration/
资料来源：Sony Mobile Blog