high definition voice (HD voice)
In fixed networks, mobile networks and the Internet, voice transmission is of inferior quality. A significant improvement is offered by new quality standards for GSM and UMTS networks that work with voice compression and are characterized by high fidelity, best speech intelligibility and voice quality. These are the two voice codecsHD Voice and Full HD Voice.
The historically defined bandwidth for analog voice transmission in fixed networks is 3.1 kHz. This low bandwidth takes into account speech intelligibility and voice recognition. Since voice quality in mobile networks is relatively low, HD-Voice achieves a voice quality that corresponds to an adequate bandwidth of 7 kHz; Full-HD-Voice is even better and corresponds to one of 20 kHz.
HD-Voice works with the voice compression Adaptive Multirate Wideband( AMR- WB). This method has been standardized by the International Telecommunication Union( ITU) under G.722 and is supported by many well-known network operators. The increased frequency range means that the high frequencies up to 7 kHz, which are crucial for speech intelligibility, are transmitted in particular. Low frequencies are also extended up to 50 Hz, which makes speech more natural.
To use HD Voice, this enhanced voice service must be supported by the network operator and also by the cell phones or smartphones. Use is only possible if both subscribers make calls with HD Voice cell phones. Since the voice compression AMR-WB is compatible with the narrowband version AMR- NB, users with different cell phones can also make calls to each other. In Germany, HD Voice is supported by Deutsche Telekom in its UMTS network.