NTT DoCoMo Develops High-Quality Speech Coding Technology for Mobile Phones


TOKYO, JAPAN, April 3, 2007 --- NTT DoCoMo, Inc. announced today that in collaboration with DoCoMo Communications Laboratories USA, Inc., it has developed speech coding technology that provides exceptionally high-quality voice for mobile phones, yet only requires the low-level computing power of conventional mobile telephony technologies.

This new technology realizes a wide frequency range of 50Hz - 16kHz, which is approximately the full range of the human voice. By comparison, the frequency range of legacy telephony services is limited to 300Hz - 3.4kHz.

The technology employs speech compression that is matched to the specific characteristics of human auditory perception, such as the fact that distortion in loud sounds is relatively imperceptible. Moreover, the technology enhances sound quality to a remarkably high degree and processes coding with great efficiency.

The resulting voice quality is so realistic that conversations via mobile phones sound as if the other person were in the same room. The technology will be especially helpful in mobile applications where voice quality is particularly critical, such as teleconferencing and remote education.

DoCoMo's "hTc Z" handset will be used to demonstrate a working version of the technology at "Telecom Summit Wireless Technology Park 2007" at the Pacifico Yokohama exhibition complex in Yokohama from April 4 to 5, 2007.

DoCoMo is continuing to develop its speech coding technology for commercialization in the foreseeable future.

DoCoMo Communications Laboratories USA is based in Palo Alto, California and focuses on research and development. It is a wholly owned subsidiary of NTT DoCoMo USA, which itself is a wholly owned subsidary of NTT DoCoMo.


About NTT DoCoMo
NTT DoCoMo is the world's leading mobile communications company. DoCoMo serves more than 52 million customers, including 34 million people subscribing to FOMA™, launched as the world's first 3G mobile service based on W-CDMA in 2001. DoCoMo also offers a wide variety of leading-edge mobile multimedia services, including i-mode™, the world's most popular mobile e-mail/Internet service, used by more than 47 million people. With the addition of credit-card and other e-wallet functions, DoCoMo mobile phones have become highly versatile tools for daily life. NTT DoCoMo is listed on the Tokyo (9437), London (NDCM) and New York (DCM) stock exchanges. For more, visit

i-mode, FOMA are trademarks or registered trademarks of NTT DoCoMo, Inc. in Japan and other countries.
NTT DoCoMo's FOMA service is only available to subscribers in Japan.

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