77 research outputs found
Integrated speech and morphological processing in a connectionist continuous speech understanding for Korean
A new tightly coupled speech and natural language integration model is
presented for a TDNN-based continuous possibly large vocabulary speech
recognition system for Korean. Unlike popular n-best techniques developed for
integrating mainly HMM-based speech recognition and natural language processing
in a {\em word level}, which is obviously inadequate for morphologically
complex agglutinative languages, our model constructs a spoken language system
based on a {\em morpheme-level} speech and language integration. With this
integration scheme, the spoken Korean processing engine (SKOPE) is designed and
implemented using a TDNN-based diphone recognition module integrated with a
Viterbi-based lexical decoding and symbolic phonological/morphological
co-analysis. Our experiment results show that the speaker-dependent continuous
{\em eojeol} (Korean word) recognition and integrated morphological analysis
can be achieved with over 80.6% success rate directly from speech inputs for
the middle-level vocabularies.Comment: latex source with a4 style, 15 pages, to be published in computer
processing of oriental language journa
Chart-driven Connectionist Categorial Parsing of Spoken Korean
While most of the speech and natural language systems which were developed
for English and other Indo-European languages neglect the morphological
processing and integrate speech and natural language at the word level, for the
agglutinative languages such as Korean and Japanese, the morphological
processing plays a major role in the language processing since these languages
have very complex morphological phenomena and relatively simple syntactic
functionality. Obviously degenerated morphological processing limits the usable
vocabulary size for the system and word-level dictionary results in exponential
explosion in the number of dictionary entries. For the agglutinative languages,
we need sub-word level integration which leaves rooms for general morphological
processing. In this paper, we developed a phoneme-level integration model of
speech and linguistic processings through general morphological analysis for
agglutinative languages and a efficient parsing scheme for that integration.
Korean is modeled lexically based on the categorial grammar formalism with
unordered argument and suppressed category extensions, and chart-driven
connectionist parsing method is introduced.Comment: 6 pages, Postscript file, Proceedings of ICCPOL'9
Disentangling Prosody Representations with Unsupervised Speech Reconstruction
Human speech can be characterized by different components, including semantic
content, speaker identity and prosodic information. Significant progress has
been made in disentangling representations for semantic content and speaker
identity in Automatic Speech Recognition (ASR) and speaker verification tasks
respectively. However, it is still an open challenging research question to
extract prosodic information because of the intrinsic association of different
attributes, such as timbre and rhythm, and because of the need for supervised
training schemes to achieve robust large-scale and speaker-independent ASR. The
aim of this paper is to address the disentanglement of emotional prosody from
speech based on unsupervised reconstruction. Specifically, we identify, design,
implement and integrate three crucial components in our proposed speech
reconstruction model Prosody2Vec: (1) a unit encoder that transforms speech
signals into discrete units for semantic content, (2) a pretrained speaker
verification model to generate speaker identity embeddings, and (3) a trainable
prosody encoder to learn prosody representations. We first pretrain the
Prosody2Vec representations on unlabelled emotional speech corpora, then
fine-tune the model on specific datasets to perform Speech Emotion Recognition
(SER) and Emotional Voice Conversion (EVC) tasks. Both objective (weighted and
unweighted accuracies) and subjective (mean opinion score) evaluations on the
EVC task suggest that Prosody2Vec effectively captures general prosodic
features that can be smoothly transferred to other emotional speech. In
addition, our SER experiments on the IEMOCAP dataset reveal that the prosody
features learned by Prosody2Vec are complementary and beneficial for the
performance of widely used speech pretraining models and surpass the
state-of-the-art methods when combining Prosody2Vec with HuBERT
representations.Comment: Accepted by IEEE/ACM Transactions on Audio, Speech, and Language
Processin
Analyzing And Improving Neural Speaker Embeddings for ASR
Neural speaker embeddings encode the speaker's speech characteristics through
a DNN model and are prevalent for speaker verification tasks. However, few
studies have investigated the usage of neural speaker embeddings for an ASR
system. In this work, we present our efforts w.r.t integrating neural speaker
embeddings into a conformer based hybrid HMM ASR system. For ASR, our improved
embedding extraction pipeline in combination with the Weighted-Simple-Add
integration method results in x-vector and c-vector reaching on par performance
with i-vectors. We further compare and analyze different speaker embeddings. We
present our acoustic model improvements obtained by switching from newbob
learning rate schedule to one cycle learning schedule resulting in a ~3%
relative WER reduction on Switchboard, additionally reducing the overall
training time by 17%. By further adding neural speaker embeddings, we gain
additional ~3% relative WER improvement on Hub5'00. Our best Conformer-based
hybrid ASR system with speaker embeddings achieves 9.0% WER on Hub5'00 and
Hub5'01 with training on SWB 300h.Comment: Accepted at ITG Speech Communications 202
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