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Gadgets & Home Improvement

The sound of HD voice

StarHub activated high definition (HD) voice, a feature that improves the overall voice quality on its mobile network.
The Straits Times - March 18, 2013
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The sound of HD voice


Background noise often interferes with voice transmission, so a caller tends to speak more loudly to be heard. This, unfortunately, distorts the signal even more.

Just as HD TV delivers sharper and clearer images, HD voice does the same for audio. It focuses on your voice and dampens the noise in the background.

In a train, for example, HD voice identifies chatter from surrounding passengers and suppresses it to focus on delivering your voice.

So you should be able to take a call where you are, instead of having to move to a quieter spot or cupping your hands over your ears.

How it works

HD voice uses wide-band audio codes to extend the range of audio frequencies supported by the regular narrow-band mobile network, which supports audio frequencies between 300Hz and 3,400Hz.

HD voice supports frequencies between 50Hz and 7,000Hz.

The channel is wider, so more soundwaves and speech data can be squeezed into it. Excess information, such as background chatter, can be stripped out, leaving only the speech information to be sent over the air.

The net result should be a more natural sounding conversation, as if you are talking in the same room.


Said a SingTel spokesman: "The difference between HD and standard voice may not be discernible to the average human ear without the use of good-quality earphones. In addition, HD voice calls are possible only if the handsets and mobile network of both calling and receiving parties are HD voice compatible."

Do not expect HD voice on land lines. The fixed line network is not HD voice-enabled and neither SingTel nor M1 has immediate plans to roll out HD voice.

What is the difference?

We used two Samsung Galaxy Note II LTE smartphones to test HD voice: DL deputy editor Sherwin Loh remained in an indoor environment with minimal background noise, while I called him on the other set from different locations with varying noise levels.

We used a HTC One XL connected to a non-HD Voice ready line to make a second call for comparison. The results are outlined in the table below.


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