User Manual

Unified Communications Microphone & Speaker System
YVC-1000 White Paper
5
1. Adaptive Echo Canceller
1.1 What is the adaptive echo canceller?
The adaptive echo canceller is a function which eliminates the sounds on the microphone side that are generated
from the speakers, and the echoes that the microphone picks up.
1.2 Superiority of YVC-1000
Although the fundamental performance of echo cancellers has been generally established, YVC-1000 is superior to
commercial conventional systems in sound quality in rooms with long reverberation times and during interactive
simultaneous communication within the HD band (100 Hz - 20 kHz).
Evaluation method:
As a method to objectively evaluate the performance of echo cancellers, Yamaha adopted the "Tdos S4-AHQ052"
method (Figure 2-1 and Table 2-1) proposed by ETSI (the European Telecommunications Standards Institute) and
thereby evaluated the echoes and the degree of losses in inserted sounds.
This method evaluates the echo canceller’s performance by comparing each time that the sound levels correspond
when the same near-end sound is picked up via the microphone’s sound pickup (the first party) without speaker
reproduction, and the microphone’s sound pickup (the second party) with speaker reproduction. If the sound level
of the second party is larger than that of the first party, it indicates that an echo is generated. If the sound level of
the second party is less than that of the first party, it indicates that an insertion loss (loss of sound volume) is
generated. An echo canceller is more excellent in performance as the absolute value of echoes and insertion losses
is small and their duration time is short.
ETSI evaluation model
(Figure 2-1)
Chapter 2
Roles and Capabilities of the Six Sound Processing Technologies