4,159 research outputs found
SCREEN: Learning a Flat Syntactic and Semantic Spoken Language Analysis Using Artificial Neural Networks
In this paper, we describe a so-called screening approach for learning robust
processing of spontaneously spoken language. A screening approach is a flat
analysis which uses shallow sequences of category representations for analyzing
an utterance at various syntactic, semantic and dialog levels. Rather than
using a deeply structured symbolic analysis, we use a flat connectionist
analysis. This screening approach aims at supporting speech and language
processing by using (1) data-driven learning and (2) robustness of
connectionist networks. In order to test this approach, we have developed the
SCREEN system which is based on this new robust, learned and flat analysis.
In this paper, we focus on a detailed description of SCREEN's architecture,
the flat syntactic and semantic analysis, the interaction with a speech
recognizer, and a detailed evaluation analysis of the robustness under the
influence of noisy or incomplete input. The main result of this paper is that
flat representations allow more robust processing of spontaneous spoken
language than deeply structured representations. In particular, we show how the
fault-tolerance and learning capability of connectionist networks can support a
flat analysis for providing more robust spoken-language processing within an
overall hybrid symbolic/connectionist framework.Comment: 51 pages, Postscript. To be published in Journal of Artificial
Intelligence Research 6(1), 199
Convolutional Neural Networks for Raw Speech Recognition
State-of-the-art automatic speech recognition (ASR) systems map the speech signal into its corresponding text. Traditional ASR systems are based on Gaussian mixture model. The emergence of deep learning drastically improved the recognition rate of ASR systems. Such systems are replacing traditional ASR systems. These systems can also be trained in end-to-end manner. End-to-end ASR systems are gaining much popularity due to simplified model-building process and abilities to directly map speech into the text without any predefined alignments. Three major types of end-to-end architectures for ASR are attention-based methods, connectionist temporal classification, and convolutional neural network (CNN)-based direct raw speech model. In this chapter, CNN-based acoustic model for raw speech signal is discussed. It establishes the relation between raw speech signal and phones in a data-driven manner. Relevant features and classifier both are jointly learned from the raw speech. Raw speech is processed by first convolutional layer to learn the feature representation. The output of first convolutional layer, that is, intermediate representation, is more discriminative and further processed by rest convolutional layers. This system uses only few parameters and performs better than traditional cepstral feature-based systems. The performance of the system is evaluated for TIMIT and claimed similar performance as MFCC
Self-Attention Networks for Connectionist Temporal Classification in Speech Recognition
The success of self-attention in NLP has led to recent applications in
end-to-end encoder-decoder architectures for speech recognition. Separately,
connectionist temporal classification (CTC) has matured as an alignment-free,
non-autoregressive approach to sequence transduction, either by itself or in
various multitask and decoding frameworks. We propose SAN-CTC, a deep, fully
self-attentional network for CTC, and show it is tractable and competitive for
end-to-end speech recognition. SAN-CTC trains quickly and outperforms existing
CTC models and most encoder-decoder models, with character error rates (CERs)
of 4.7% in 1 day on WSJ eval92 and 2.8% in 1 week on LibriSpeech test-clean,
with a fixed architecture and one GPU. Similar improvements hold for WERs after
LM decoding. We motivate the architecture for speech, evaluate position and
downsampling approaches, and explore how label alphabets (character, phoneme,
subword) affect attention heads and performance.Comment: Accepted to ICASSP 201
A Study of All-Convolutional Encoders for Connectionist Temporal Classification
Connectionist temporal classification (CTC) is a popular sequence prediction
approach for automatic speech recognition that is typically used with models
based on recurrent neural networks (RNNs). We explore whether deep
convolutional neural networks (CNNs) can be used effectively instead of RNNs as
the "encoder" in CTC. CNNs lack an explicit representation of the entire
sequence, but have the advantage that they are much faster to train. We present
an exploration of CNNs as encoders for CTC models, in the context of
character-based (lexicon-free) automatic speech recognition. In particular, we
explore a range of one-dimensional convolutional layers, which are particularly
efficient. We compare the performance of our CNN-based models against typical
RNNbased models in terms of training time, decoding time, model size and word
error rate (WER) on the Switchboard Eval2000 corpus. We find that our CNN-based
models are close in performance to LSTMs, while not matching them, and are much
faster to train and decode.Comment: Accepted to ICASSP-201
Advances in Joint CTC-Attention based End-to-End Speech Recognition with a Deep CNN Encoder and RNN-LM
We present a state-of-the-art end-to-end Automatic Speech Recognition (ASR)
model. We learn to listen and write characters with a joint Connectionist
Temporal Classification (CTC) and attention-based encoder-decoder network. The
encoder is a deep Convolutional Neural Network (CNN) based on the VGG network.
The CTC network sits on top of the encoder and is jointly trained with the
attention-based decoder. During the beam search process, we combine the CTC
predictions, the attention-based decoder predictions and a separately trained
LSTM language model. We achieve a 5-10\% error reduction compared to prior
systems on spontaneous Japanese and Chinese speech, and our end-to-end model
beats out traditional hybrid ASR systems.Comment: Accepted for INTERSPEECH 201
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