@InProceedings{Schmidt2018_422,
author = {Gerhard Schmidt},
booktitle = {Studientexte zur Sprachkommunikation: Elektronische Sprachsignalverarbeitung 2018},
title = {In-Car (Voice) Communication: Problems, Solutions, and Challenges},
year = {2018},
editor = {André Berton and Udo Haiber and Wolfgang Minker},
month = mar,
pages = {309--309},
publisher = {TUDpress, Dresden},
abstract = {Voice communication in cars is impaired by several factors. Depending on the driving speed a
moderate or even high level of background noise superposes to the speech signals generated by
the passengers or by loudspeakers that emit the signals from communication partners connected
via mobile phone connections. Due to the seat adjustment (position and orientation) the front
passengers do not speak into the direction of the rear passengers and face-to-face
communication among the passengers is not as easy as in a “normal” communication.
If so-called ICC systems (ICC abbreviates in-car communication) are used, the passengers are
recorded using microphones. After appropriate signal processing (mainly noise, echo, and
feedback reduction) the enhanced signals of the talkers are played back via loudspeakers close
to the ears of the listening passengers. At first glance such systems face the same problems as
hands-free or speech dialog systems but due to the closed electro-acoustic loop that they have to
operate in special problems arise, e.g. correlation of the local signals with the loudspeaker
signals that lead to problems when performing system identification with adaptive filters.
Furthermore, the enhancement usually leads to a better signal-to-noise ratio at the ears of the
listeners. However, the more the signal-to-noise ratio is improved for the listening passengers
the more the speaking passengers are aware of or even disturbed by their own voices due to
echo perception.
In this talk I will try to mention most of the challenges that one faces when building combined
in-car communication/hands-free/speech-dialog systems. The solution to these challenges is
usually a “cocktail” of individual processing units where the ingredients are low-delay
filterbanks, adaptive structures for system identification, spectral suppression rules,
decorrelation schemes, and adaptive mixing approaches. In most cases a compromise between
the needs of the talking and the listening passengers has to be found which makes this
application a very interesting challenge.
If one combines pure ICC systems with other speech and audio systems in a car such as handfree,
anti-noise, or music playback systems the complexity of the resulting system increases.
However, the system components mentioned before can be combined such that they can
overcome some of the problems, which is again an interesting challenge.
Let me finally mention that even after decades of great and continuous improvement in speech
and audio signal processing the communication of passengers in a car driven at medium speed
could still be improved. Thus, speech signal enhancement remains “a rocky road” – to say it
with the words of one of the early German speech processing researches.},
isbn = {978-3-959081-28-3},
issn = {0940-6832},
keywords = {Hauptvortrag},
url = {https://www.essv.de/pdf/2018_309_309.pdf},
}