Wideband Hands-Free in Cars – New Challenges for System Design and Testing - Digital Signal Processing for In-Vehicle Systems and Safety - page 103

Chapter 6
Wideband Hands-Free in Cars - New
Challenges for System Design and Testing

Hans W. Gierlich and Frank Kettler

Abstract Wideband hands-free technology in cars provides the capability to
substantially improve the quality of the perceived speech for the driver as well as
for the far-end communicational partner. However, in order to achieve a superior
wideband speech quality, a variety of requirements - different from narrowband
telephony - have to be taken into account. A few important parameters most critical
for the success of wideband in cars are discussed. Since wideband transmission is at
least partially IP-based, a higher delay can be expected as compared to narrowband
calls. The impact of higher delay on the communicational quality is shown, and the
different elements contributing to the delay in car hands-free systems are shown.
Also, the impact of delay on conversational quality is discussed. The other aspects
of wideband communication include speech sound quality in sending and receiving
direction. A new objective test procedure 3QUEST for speech quality with back-
ground noise and its application to wideband car hands-free is introduced. For
echo performance in wideband, new subjective test results are shown, and results
of a new objective echo analysis method based on the hearing model “Relative
Approach” are shown.

Keywords Human perception ￿ System design ￿ Wideband hands-free technology

6.1 Introduction

The deployment of wideband hands-free technology in cars provides the capability
to substantially improve the quality of perceived speech for the driver as well as for
the far-end communicational partner. In-vehicle hands-free terminals would benefit
from wideband than traditional communication terminals. The difference in sound

H.W. Gierlich ( * ) ￿ F. Kettler
HEAD Acoustics GmbH, Herzogenrath, Germany
e-mail: [e-mail]