Skype is to license for free a high-quality audio codec in its latest VoIP software to any developer or vendor.

Called Silk, the "super-wideband" codec delivers a sound quality that captures the full sound of the human voice.

Jonathan Christensen, Skype’s general manager of audio and video, launched the licensing program earlier this week at the eComm conference in California.

He said that the normal phone system uses a narrow band for voice, from 400Hz to 3,400Hz, that cuts off high and low frequencies.

Silk allows Skype to reproduce the full range of typical voice frequencies audible to the human ear, from 50Hz to 12,000Hz.

So, while traditional systems carry voice in a standard 64Kb per second (Kbps) channel – which has disadvantages, such as blurring the difference between similar sounds such as "f" and "s" – VoIP can be carried in a fatter pipe.

This has allowed new codecs to be written to encode and decode voice at higher quality.

Benefits of this include helping callers identify different speakers on conference calls and making calls sound generally warmer, according to Christensen.

Additionally, the new codec requires half the network bandwidth of Skype’s previous version.

Christensen said the codec will be made freely available to third-party developers. They will be able to use it in any device or application, with or without Skype.

"We think this is a way the whole industry can come up to a new standard of voice quality," he said.

Skype’s motivation for making Silk available for free is to expand the range of hardware and software clients its calling software works with by establishing a common codec for clients to adopt.

This goes from PC software, headsets and videoconferencing systems to cordless phones and mobiles.

Silk runs on x86 chipsets for Windows, Macintosh and Linux systems, and the software has been run on Arm and MIPS chip platforms.

It is currently available as Skype 4.0 for Windows and as a Macintosh beta version 2.8. A final Mac version and one for Linux are due in April.

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