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A Slippery Slope of HD Audio, HD Voice and HD VoIP

May 12, 2011

By Doug Mohney, Contributing Editor

When it comes to phones, people are starting to throw around “HD” fast and loose, using a wide range of terms such as “HD audio,” “HD voice,” and “HD VoIP.”   It’s all starting to drive me crazy, because people and companies are starting to say one thing when they might mean another, leading to a rat race of clarifications.

For the past two years, the working definition of “HD voice” that I and most others in the industry have used is a phone call/conversation that uses/delivers at least twice the sound as compared to a narrowband call.   More precisely, this means a narrowband call samples at 8 kHz, while an HD voice call samples at 16 kHz. A narrowband call delivers sound in a range between 300 Hz to 3400 Hz while a HD voice call delivers a sound in the range of about 50 Hz to 7000 Hz or better.

For codec geeks, narrowband voice is G.711 while HD voice is G.722 or better. I use HD voice and wideband voice interchangeably, since both terms mean the same thing when using the definition above.

HD VoIP has had favor in some circles, with AudioCodes being the biggest advocate of the term. AudioCodes prefers HD VoIP to set IP calls apart from wideband voice calls delivered over ISDN using the G.722 codec.  I’ve shied away from using HD VoIP because it reminds me of the whole “Voice over” <blank> discussions back a decade ago (Voice over DSL, Voice over Cable, now we’re into Voice over LTE). Since voice transmission is converging onto VoIP anyway, I’m sticking to HD voice for the next five minutes.

Finally, we come to the term HD audio which brings forth “Intel High Definition Audio” from Wikipedia, as well as a larger relationship with Hifi, stereo components, CD quality sound, HD radio, and many other headaches. If you’re using the AAC codec, does that make you HD audio when you’re playing music and HD voice when you’re in a conferencing application?

See the headaches?

For clarity, I believe the best solution would be to coin a new term specifically to phone/voice communication: HD telephony. I’m doubtful the term will catch on, however, because the soft client bigots don’t want to associate with “telephony” and the rest of the world is too busy creatively mixing up the usage of HD audio and HD voice, with an occasional HD VoIP thrown in for good measure.

Doug Mohney is a contributing editor for virtual-pbx and a 20-year veteran of the ICT space. To read more of his articles, please visit columnist page.

Edited by Jennifer Russell

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