M. Yamada et al., A SPOKEN DIALOG SYSTEM WITH ACTIVE NON-ACTIVE WORD CONTROL FOR CD-ROMINFORMATION-RETRIEVAL, Speech communication, 15(3-4), 1994, pp. 355-365
This paper describes a development of a spoken dialogue travel guidanc
e system, TARSAN. TARSAN uses commercial CD-ROM guidebooks as its know
ledge source, containing a large amount of travel information. To deal
with this amount of information, a large vocabulary has to be accepte
d by a speech recognizer without reducing its performance. Thus, we pr
opose two steps of active/non-active word control methods: (1) a word/
grammar prediction strategy, and (2) unknown word re-evaluation algori
thm. The word/grammar prediction strategy dynamically changes a recogn
ition network according to a conversation situation by making use of r
esults retrieved from the CD-ROMs. This strategy makes users to access
almost all data on the CD-ROMs using a small vocabular speech recogni
zer. The unknown word re-evaluation algorithm processes unknown words
and non-active words using Garbage Models by integrating them into the
recognition network, and once the Garbage Models are recognized, the
unknown part will be compared with the non-active words. This algorith
m enhances the ability of the word/grammar prediction. In the experime
nt without Garbage Models, 80.9% of the utterances were correctly unde
rstood. In the unknown word re-evaluation experiment using the Garbage
Models, 86.4% were correctly re-evaluated, while the false alarms of
5% were found.