原來 Xperia T 是 HD Voice Certified，一個 GSMA 的認証！即是在一個嘈雜的環境下通話，你只要如常地說話，無需加大聲量，對方也可以聽得清清楚楚。
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?
其實 HD Voice 不是新科技，之前已有一些手機支援，例如：Xperia Arc, Neo, Play 等，Nokia N8, C7 也支援的。不過，要用 HD Voice 也要通話雙方和網絡支援才可應用。
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.
若有興趣可以到 GSMA 網站聆聽一下 HD Voice Sound Demo。
http://www.gsma.com/technicalprojects/hd-voice-sound-demonstration/
資料來源：Sony Mobile Blog