Wideband Audio Reference Guide

Business Issue/Requirement

Traditional telephone instruments and networks carry audio frequencies in narrowband — the range of 300 to 3400 Hertz — a significantly narrower range than the human voice. This is why, for example, when you listen to a talk radio show, you hear a great distinction between the participants in the studio and those calling in, who often are heard in comparatively poor quality.

Compromised audio quality is especially significant in audio conferencing, where it becomes much more difficult to recognize voices, understand accented speakers, and overcome background noise and other impairments often associated with conference room acoustics. These challenges often lead to misunderstandings, confusion and requests to repeat things. In almost all cases, call participants become fatigued, because their brains are subconsciously distracted trying to restore the audio to an intelligible level and understand everything being said. More attention and energy is expended for the act of listening, as opposed to understanding and participating. Therefore, calls are not as productive as they could be.

New telephone equipment, including both handsets and conference room speakerphones, is now able to capture and reproduce audio at frequencies as low as 30 Hertz and as high as 7000 Hertz (or higher in some cases). This doubling of the audio spectrum makes speech sound much more natural and addresses the issues listed above. This larger range is based on wideband audio, a tremendous improvement in sound quality.

NB vs WB

A conferencing service should be able to work in conjunction with new equipment to deliver the highest possible audio quality. At the same time, it should also allow callers using phones without the latest technology to connect (since so frequently, some participants will be in their cars or in offices that lack enhanced equipment). In these “mixed mode” conferences, it is critical that the “wideband” participants hear each other in wideband, even though the others will sound like callers to the talk-radio program. The service should offer all the same features and services to both wide- and narrowband callers, and it should not introduce any noticeable latency (delay) in the conversation due to the conversion between the two types of audio encoding.

ZipDX Feature

ZipDX is the only teleconference service to fully support standards-based wideband audio. It does this via the ITU G.722 audio coding standard, the most widely adopted high-fidelity telephony codec that has been adopted by a broad range of equipment manufacturers, including Polycom, Cisco, Avaya, Snom and others.

ZipDX allows connections to the same conference via both SIP (a Voice Over IP – VoIP-technology) and the traditional public telephone network (Public Switched Telephone Network-PSTN). Wideband participants will typically use SIP, while narrowband participants can use either network. ZipDX will preserve the highest possible fidelity, rather than operating at the “lowest common denominator. “

Wideband is automatically enabled in ZipDX; if a participant’s telephone is equipped and configured for wideband, ZipDX will take advantage of it. For participants with wideband capability, ZipDX announces “now joining in wideband” and displays a special icon on the dashboard.

Use this Feature

If wideband participants are using a high-quality telephone, the higher fidelity of wideband will be obvious. Participants may immediately notice the improvement to consonant sounds like “s” and “f,” which sound much clearer in wideband. Also with wideband, when someone is speaking softly, or is facing away from a table-top speakerphone, it is much easier to make out what they are saying. Having a call with participants from the US, Asia, India and Europe? The clarity of wideband does wonders for helping to better understand accented speakers.

Also be aware that the ZipDX recording feature (see Section 8 ‘Call Recording’) captures in wideband, so the enhanced audio is preserved and will be a benefit to future listeners. Some PC speakers may not do justice to the quality, but headsets almost always provide ample fidelity.

A Wideband Demo
To listen to ZipDX’s wideband demonstration, dial this SIP URI from a G.722-capable (wideband) telephone connected to the public Internet: wbdemo@zipdx.com

A recording will confirm that you are connected in wideband, and will then play a demo. You can toggle between wideband and narrowband by pressing the “#” key. A variety of other playback material is also available; press “0” to hear instructions.