Title
Investigation on N-Gram Approximated RNNLMs for Recognition of Morphologically Rich Speech.
Abstract
Recognition of Hungarian conversational telephone speech is challenging due to the informal style and morphological richness of the language. Recurrent Neural Network Language Model (RNNLM) can provide remedy for the high perplexity of the task; however, two-pass decoding introduces a considerable processing delay. In order to eliminate this delay we investigate approaches aiming at the complexity reduction of RNNLM, while preserving its accuracy. We compare the performance of conventional back-off n-gram language models (BNLM), BNLM approximation of RNNLMs (RNN-BNLM) and RNN n-grams in terms of perplexity and word error rate (WER). Morphological richness is often addressed by using statistically derived subwords - morphs - in the language models, hence our investigations are extended to morph-based models, as well. We found that using RNN-BNLMs 40% of the RNNLM perplexity reduction can be recovered, which is roughly equal to the performance of a RNN 4-gram model. Combining morph-based modeling and approximation of RNNLM, we were able to achieve 8% relative WER reduction and preserve real-time operation of our conversational telephone speech recognition system.
Year
DOI
Venue
2019
10.1007/978-3-030-31372-2_19
SLSP
Field
DocType
Citations 
Perplexity,Computer science,Word error rate,Recurrent neural network,Reduction (complexity),Speech recognition,n-gram,Decoding methods,Language model,Processing delay
Conference
0
PageRank 
References 
Authors
0.34
0
4
Name
Order
Citations
PageRank
Balázs Tarján1214.92
György Szaszák25113.21
Tibor Fegyó36110.46
Péter Mihajlik45810.15