Wideband voice

Wideband voice refers to the use of wideband codecs in digital telephony. Wideband codecs use higher sampling rates than ordinary narrowband (voiceband) codecs or utilize embedded sub-band coding techniques to effectively increase the bandwidth of the baseband voice, from the traditional 200 Hz to 3.5 kHz voiceband used in narrowband codecs, to 50 Hz at the low end and anywhere from 7 kHz to 22 kHz. at the high end, depending on the type of codec used. This results in a significant improvement in voice quality since it allows the wideband codec to transmit consonants, sibilants and other subtleties of the human voice formerly lost by narrowband codecs and significantly adds to the intelligibility and quality of the speech signal.

In addition, some wideband codecs may use a higher audio bit depth of 16-bits to encode samples, also resulting in much better voice quality.

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Wideband audio

Wideband audio, also known as HD voice, is high definition voice quality for telephony audio, contrasted with 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.

History

In 1987, the International Telecommunication Union (ITU) standardized a version of wideband audio known as G.722. Radio broadcasters began using G.722 over Integrated Services Digital Network (ISDN) to provide high-quality audio for remote broadcasts, such as commentary from sports venues. AMR-WB (G.722.2) was developed by Nokia and VoiceAge and it was first specified by 3GPP.

The traditional telephone network (PSTN) is generally limited to narrowband audio by the intrinsic nature of its transmission technology, TDM (time-division multiplexing), and by the analogue-to-digital converters used at the edge of the network, as well as the speakers, microphones and other elements in the endpoints themselves.