HD Voice Technology

Wideband audio, or HD voice, refers to the next generation of voice quality for telephony audio resulting in high definition voice quality compared to standard digital telephony “toll quality”. It extends the frequency range of audio signals transmitted over telephone lines, resulting in higher quality speech. The range of the human voice extends from 80 Hz to 14 kHz but traditional, voiceband or narrowband telephone calls limit audio frequencies to the range of 300 Hz to 3.4 kHz. Wideband audio relaxes the bandwidth limitation and transmits in the audio frequency range of 50 Hz to 7 kHz or higher.


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.

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.

Most of the latest smartphones now support HD Voice, including the iPhone 5, Samsung S III (and IV), HTC One, Nokia Lumia 920 and Sony Xperia Z. All of the phones have speakers and microphones that support wideband audio.


There is a catch, however. HD Voice won’t be interoperable to start. That means both phones on the call must support HD Voice and share a carrier that supports HD Voice. That means if you have an iPhone 5 on AT&T and you’re calling someone with an iPhone 5 on Sprint, you won’t get an HD Voice-quality call.

More Samples per Second…. improving Audio Quality

HD Voice also takes in more audio samples per second than a standard call. Instead of 8,000 audio samples per second, HD Voice calls double that to 16,000. That way, you’re able to hear more details in a person’s voice during a call.

Some listener benefits cited of wideband audio compared to traditional (narrowband):

  • clearer overall sound quality
  • easier to recognize voices, distinguish confusing sounds and understand accented speakers
  • ease of deciphering words that have the close sounds of ‘s’ and ‘f’ and others, often indistinguishable over telephone lines
  • ability to hear faint talkers and to understand double-talk (when more than one person is speaking at the same time)
  • reduced listening effort (decreased cognitive load), resulting in increased productivity and lessened listener fatigue
  • better understanding in the face of other impairments, such as when talkers are using a speakerphone or in the presence of background noise

Courtesy: wikipedia.org, gizmodo.com, wired.com

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