Wideband Audio

Wideband audio extends the frequency range of sound traveling over telephone lines, resulting in higher quality voice transmission. The range of the human voice extends from 80 hertz to 14,000 hertz. Traditional, or narrowband telephone calls, limit audio frequencies to the range of 300 to 3400 hertz. Wideband audio eliminates the majority of bandwidth limitations and transmits in the range of 30 hertz to 7000 hertz or higher.

In 1987, the International Telecommunication Union (ITU) standardized a version of wideband audio as G.722. Radio broadcasters began using G.722 over Integrated Services Digital Network (ISDN) to provide high-quality audio from remote locations, such as sports venues.

The traditional telephone network (PSTN) is generally limited to narrowband audio by the analog-to-digital converters used at the edge of the network, as well as the speakers, microphones and other elements in the endpoints themselves.

Wideband audio has been broadly deployed in conjunction with video conferencing. Providers of this technology quickly discovered that despite the explicit emphasis on video transmission, the quality of the participant experience was significantly influenced by the fidelity of the associated audio signal.

Communications via Voice over Internet Protocol (VoIP) can readily employ wideband audio. When PC-to-PC calls are placed via VoIP services, such as Skype, and the participants use a high-quality headset, the resulting call quality can be notably superior to conventional PSTN calls. A number of audio codecs have emerged to support these services, supplementing G.722.

Manufacturers of audio conferencing equipment have introduced wideband-capable models that include support for G.722 over VoIP.

Conference calls are a direct beneficiary of the enhancements offered by wideband audio. Participants often struggle to figure out who is talking, or to understand accented speakers. Misunderstandings are commonplace due primarily to generally poor audio quality and an accumulation of background noise.

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)
*More attention can be given to the call content and less brain function to try hearing what people are saying; resulting in increased productivity and less fatigue on business calls
*Better understanding in the face of other impairments, such as when talkers are using a speakerphone or in the presence of background noise

Despite its reputation for poor audio quality, the mobile telephone industry has started to make some progress on wideband audio. The 3GPP standards group has designated G.722.2 as its wideband codec and calls it Advanced Multirate – Wideband (AMR-WB). A few handsets have been produced supporting this codec (for example, Nokia), and network demonstrations have been conducted.

Deployment

As business telephone systems have adopted VoIP technology, support for wideband audio has grown rapidly. Telephone sets from Avaya, Cisco, Grandstream, Polycom, Snom, and others now incorporate G.722, as well as varying degrees of higher-quality audio components.

Suppliers of integrated circuits for telephony equipment, including Broadcom, Infineon, and Texas Instruments, include wideband audio in their feature portfolios.

ZipDX [http://www.ZipDX.com] is an audio conferencing service provider that supports wideband connections from these and other VoIP endpoints, while also permitting PSTN participants to join the conference in narrowband.

Service Providers and Vendors

Avaya, Cisco, Grandstream [http://www.grandstream.com] , Polycom, Snom,
Broadcom, Infineon, Texas Instruments,ZipDX [http://www.ZipDX.com]

References

*International Telecommunications Union
*TMCNet.com HD Voice Community [http://hdvoice.tmcnet.com/]
*InfoWorld [http://weblog.infoworld.com/realitycheck/archives/2007/11/voip_transition.html]
*Texas Instruments [http://focus.ti.com/download/bcg/HDvoice.html]
*IDC Whitepaper [http://www.polycom.com/common/documents/whitepapers/can_you_hear_what_i_mean_polycom_delivers_hd_voice.pdf?id=HD_Voice&link=TMC] ]
*Whitepaper: The Effect of Bandwidth of Speech Intelligibility [http://www.polycom.com/common/documents/whitepapers/effect_of_bandwidth_on_speech_intelligibility_2.pdf?id=HD_Voice&link=TMC] ]