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ITU 150

Question 16/16

Question 16/16 – Speech enhancement functions in signal processing network equipment

(Continuation of Question 16/16)


This Question deals with network-based speech enhancement devices, including electrical network echo control, acoustic network echo control, automatic level control devices, and speech enhancement devices.

The application of echo cancellers continues to evolve in existing general switched telephone networks (GSTN), cellular, ATM and emerging IP networks. These applications bring new issues to echo canceller performance, and will require study to ensure that network operators have adequate assurance of transmission quality from echo cancellers complying with ITU-T G.168. These issues may result in adding and improving the tests within ITU-T G.168, and studying the issues arising from the deployment of echo cancellers to ATM and IP networks and new services within the GSTN.

With the deployment of automatic level control (ALC) and voice enhancement devices (VEDs), new issues are expected to arise as these devices are applied to existing and emerging networks. As a result, Recommendations ITU T G.160 and G.169 may need to be revised to continue to ensure adequate transmission quality.

As echo cancellers are embedded into gateways it will become necessary to review the applicability of ITU-T G.168 to these devices and to develop either a separate Recommendation or Annex to ITU T G.168 to ensure that any specific requirements for these embedded echo cancellers are taken into account.

The Question will attempt to work electronically where possible and to make full use of e-mail and conferencing facilities in an attempt to reduce its carbon footprint.

Study items

Study items to be considered include, but are not limited to:


Tasks include, but are not limited to:

An up-to-date status of work under this Question is found in the SG 16 work programme (