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Date: Tue, 28 Feb 95 14:07:11 EST
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Subject: Postdoc: Speech Dialog at Erlangen-Nuerenberg University
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From: lieske@forwiss.uni-erlangen.de (Christian Lieske)
Subject: post-doctoral fellowships HCM/MSDoS at Erlangen-Nuernberg University
Date: Fri, 24 Feb 1995 09:46:46 GMT
Organization: Regionales Rechenzentrum Erlangen, Germany

== post-doctoral fellowships HCM/MSDoS at Erlangen-Nuernberg University ==

MSDoS -- Modelling Spontaneous Dialogs of Speech

Spontaneous speech is a very important research topic if speech
technology is to be used in real applications. Even though there are
well known large differences between read speech and spontaneous speech,
our presently available speech understanding and dialog system 
EVAR -- like most other
systems -- assumes grammatically correct input. Typical phenomena of
spontaneous speech that make it ungrammatical are corrections, filled
pauses, restarts, non-speech phenomena, ungrammatical order of
constituents. In addition, words can occur that are 
unknown to the recognition system. 

Recognition results can greatly be improved using stochastic language
models (Again most results for language models refer to read speech).
These models give for each word of the recognition lexicon
a probability of appearence, given the words uttered so far.
Normally this is approximated by estimating these probabilities for a
large training corpus, given the last
or the last 2 words. This approach
is to be adopted for spontaneous speech.

Another important research topic is a greater robustness
and flexibility of 
currently implemented dialog systems especially with respect
to the handling of user-interrupts for topic shift.
Topic shifts imply a change in the language model used for
recognition. The fact that there is a topic shift has to be decided by
the dialog module based on the results from the word recognition
module. Thus these two tasks are losely coupled.

The necessary steps include:

* Collection and transliteration 
of a corpus of spontaneous human-machine-dialogs. 
This is to be done,
using our EVAR system. 

* Creation of a language model for spontaneous
speech that takes the spontaneous speech phenomena
described above into account. The main problem will be
how to process partially uttered words, unknown word, and non-speech
events, i.e. how to process parts of speech that cannot be analyzed and
create a language model of high predictive power for the following
speech events.

* Extension of the current dialog system to achieve greater robustness
and flexibility. For this a
careful analysis of the user input that leads to system errors
and an incremental improvement of the system has to be done.
We expect the system to have a initial failure rate of app. 40\%.
This is not surprising because the system was not trained so far with 
spontaneous dialogs. Certain discourse behaviors like topic shift
are not modelled yet in the system. The necessary steps include
changes in the dialog memory and adaptation of the recognition 
module in order to recognize special
vocabulary indicating topic shift.

For these tasks we have two HCM post-doctoral fellowships
for a duration of 9 month each. 
The task of collecting a speech corpus will be split between
the two researchers. It is planned that the researcher working
on language models will 
start working app. one year before the person working on the dialog
robustness who can then already start working on the first
part of the corpus. 
This second researcher can then collect his data with the already
improved version of EVAR.

Together with 5 other research groups we applied for the HCM network
``SPIN -- Spontaneous Speech Recognition in Real Environments''.
If this network is accepted, the two researchers from the MSDoS proposal
will greatly benefit from a close cooperation with 
the researchers involved in the
SPIN network. However, even though the topics covered in the two 
proposals are strongly related to each other, there is no overlap
of the research tasks
between the MSDoS proposal and the SPIN network.
Both proposals can be worked upon independently.

People interested in the Project should
write to:

Prof. Dr.-Ing. H. Niemann
Lehrstuhl fuer Mustererkennung (Informatik 5)
Universitaet Erlangen-Nuernberg
Martensstrasse 3
D-91058 Erlangen
F.R. of Germany 

e-mail: niemann@informatik.uni-erlangen.de

or to

Elmar Noeth
Lehrstuhl fuer Mustererkennung (Informatik 5) 
Universitaet Erlangen-Nuernberg 
Martensstrasse 3 
D-91058 Erlangen 
F.R. of Germany 

e-mail: noeth@informatik.uni-erlangen.de

---
Christian Lieske               |Tel.: 049/9131/691 137
	                       |Fax.: 049/691 185
Bayerisches Forschungszentrum  |
fuer wissensbasierte Systeme   |
- FORWISS -                    |
Am Weichselgarten 7            |
                               |
D-91058 Erlangen-Tennenlohe    |




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