What Is HD Voice?

As people increasingly abandon voice calling for texting and emailing, audio quality has been a bit neglected. But Sprint's debut of the HD voice-compatible Evo 4G LTE signals that carriers are starting to kick the quality up a notch. The jump from your current phone to HD voice is like switching from dialup to DSL—but what is it, exactly?

HD voice is a wideband audio technology…

Normally, calls are transmitted on a limited frequency of 300 Hz to 3.4 kHz. But HD voice is a wideband audio technology, expanding that range from 50 Hz to 7 kHz and up. This larger frequency essentially means that more soundwaves and speech data can be squeezed into a single channel, with the excess information is stripped out, resulting in clearer calls.

For for those of you into the nitty gritty, the standard for wideband audio—established by the International Telecommunications Union (ITU) in 1988—is G.722. Achieved through a speech-compression algorithm called AMR-WB, this provides for extended frequency of audio calls. This speech codec was originally developed by Nokia and Voice Age.

…originally used for conference calls…

If you've ever participated in a conference call, you know how confusing it can be. It's hard to tell who's talking, background noise interrupts, and statements are misunderstood or lost in the shuffle. However, wideband audio makes sound clearer and crisper. The voice of the speaker is recognizable, accents are more readily deciphered, superfluous noise is cut out, and it's easier to hear people talking over one another.

HD voice has also started to pop up on VoIP, though the emphasis is of course on the video. Skype, for example, employs HD voice through an audio codec called Silk.

…and now appearing in smartphones and on major carriers…

This week Sprint showed off the HTC Evo 4G LTE, its first HD voice-compatible phone. But Sprint won't roll out HD voice until mid-year, and both people on a call will have to have HD voice devices to enjoy the richer, fuller sounds.

Sprint has plans to expand HD voice offerings, beginning a nationwide network rollout by the end of the year. Verizon also plans to add HD voice to its network in 2012. So if you're in the US, you're going to have to wait a bit to reap its benefits

Mobile users in the Europe, however, already have HD voice. U.K. carrier Orange, for one, upped the quality in September 2010.

…that vastly improves audio quality.

It's not just hype; there is a monumental difference between audio quality on HD voice as opposed to regular calling.

In a recent ears-on with HD voice, our Brent Rose described sounds as louder and more lifelike, with loud background noises hushed. The most obvious comparison would be watching television on a regular set versus a high-def model. The picture quality is sharper and much more beautiful, bettering the overall viewer experience. HD voice does this for audio, and hopefully, we'll be hearing these souped-up sounds in more places, from more carriers, within the year.

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