342 research outputs found
HMM-based Non-native Accent Assessment using Posterior Features
Automatic non-native accent assessment has many potential benefits in language learning and speech technologies. The three fundamental challenges in automatic accent assessment are to characterize, model and assess individual variation in speech of the non-native speaker. In our recent work, accentedness score was automatically obtained by comparing two phone probability sequences obtained through instances of non-native and native speech. In this paper, we build on the previous work and obtain the native latent symbol probability sequence through the word hypothesis modeled as a hidden Markov model (HMM). The approach overcomes the necessity for a native human reference speech of the same sentence. Using the HMMs trained on an auxiliary native speech corpus, the proposed approach achieves a correlation of 0.68 with the human accent ratings on the ISLE corpus. This is further interesting considering that the approach does not use any non-native data and human accent ratings at any stage of the system development
Recognizing Speech in a Novel Accent: The Motor Theory of Speech Perception Reframed
The motor theory of speech perception holds that we perceive the speech of
another in terms of a motor representation of that speech. However, when we
have learned to recognize a foreign accent, it seems plausible that recognition
of a word rarely involves reconstruction of the speech gestures of the speaker
rather than the listener. To better assess the motor theory and this
observation, we proceed in three stages. Part 1 places the motor theory of
speech perception in a larger framework based on our earlier models of the
adaptive formation of mirror neurons for grasping, and for viewing extensions
of that mirror system as part of a larger system for neuro-linguistic
processing, augmented by the present consideration of recognizing speech in a
novel accent. Part 2 then offers a novel computational model of how a listener
comes to understand the speech of someone speaking the listener's native
language with a foreign accent. The core tenet of the model is that the
listener uses hypotheses about the word the speaker is currently uttering to
update probabilities linking the sound produced by the speaker to phonemes in
the native language repertoire of the listener. This, on average, improves the
recognition of later words. This model is neutral regarding the nature of the
representations it uses (motor vs. auditory). It serve as a reference point for
the discussion in Part 3, which proposes a dual-stream neuro-linguistic
architecture to revisits claims for and against the motor theory of speech
perception and the relevance of mirror neurons, and extracts some implications
for the reframing of the motor theory
Automatic Pronunciation Assessment -- A Review
Pronunciation assessment and its application in computer-aided pronunciation
training (CAPT) have seen impressive progress in recent years. With the rapid
growth in language processing and deep learning over the past few years, there
is a need for an updated review. In this paper, we review methods employed in
pronunciation assessment for both phonemic and prosodic. We categorize the main
challenges observed in prominent research trends, and highlight existing
limitations, and available resources. This is followed by a discussion of the
remaining challenges and possible directions for future work.Comment: 9 pages, accepted to EMNLP Finding
Leveraging phone-level linguistic-acoustic similarity for utterance-level pronunciation scoring
Recent studies on pronunciation scoring have explored the effect of
introducing phone embeddings as reference pronunciation, but mostly in an
implicit manner, i.e., addition or concatenation of reference phone embedding
and actual pronunciation of the target phone as the phone-level pronunciation
quality representation. In this paper, we propose to use linguistic-acoustic
similarity to explicitly measure the deviation of non-native production from
its native reference for pronunciation assessment. Specifically, the deviation
is first estimated by the cosine similarity between reference phone embedding
and corresponding acoustic embedding. Next, a phone-level Goodness of
pronunciation (GOP) pre-training stage is introduced to guide this
similarity-based learning for better initialization of the aforementioned two
embeddings. Finally, a transformer-based hierarchical pronunciation scorer is
used to map a sequence of phone embeddings, acoustic embeddings along with
their similarity measures to predict the final utterance-level score.
Experimental results on the non-native databases suggest that the proposed
system significantly outperforms the baselines, where the acoustic and phone
embeddings are simply added or concatenated. A further examination shows that
the phone embeddings learned in the proposed approach are able to capture
linguistic-acoustic attributes of native pronunciation as reference.Comment: Accepted by ICASSP 202
Automated assessment of second language comprehensibility: Review, training, validation, and generalization studies
Whereas many scholars have emphasized the relative importance of comprehensibility as an ecologically valid goal for L2 speech training, testing, and development, eliciting listeners’ judgments is time-consuming. Following calls for research on more efficient L2 speech rating methods in applied linguistics, and growing attention toward using machine learning on spontaneous unscripted speech in speech engineering, the current study examined the possibility of establishing quick and reliable automated comprehensibility assessments. Orchestrating a set of phonological (maximum posterior probabilities and gaps between L1 and L2 speech), prosodic (pitch and intensity variation), and temporal measures (articulation rate, pause frequency), the regression model significantly predicted how naïve listeners intuitively judged low, mid, high, and nativelike comprehensibility among 100 L1 and L2 speakers’ picture descriptions. The strength of the correlation (r = .823 for machine vs. human ratings) was comparable to naïve listeners’ interrater agreement (r = .760 for humans vs. humans). The findings were successfully replicated when the model was applied to a new dataset of 45 L1 and L2 speakers (r = .827) and tested under a more freely constructed interview task condition (r = .809)
A computational model for studying L1’s effect on L2 speech learning
abstract: Much evidence has shown that first language (L1) plays an important role in the formation of L2 phonological system during second language (L2) learning process. This combines with the fact that different L1s have distinct phonological patterns to indicate the diverse L2 speech learning outcomes for speakers from different L1 backgrounds. This dissertation hypothesizes that phonological distances between accented speech and speakers' L1 speech are also correlated with perceived accentedness, and the correlations are negative for some phonological properties. Moreover, contrastive phonological distinctions between L1s and L2 will manifest themselves in the accented speech produced by speaker from these L1s. To test the hypotheses, this study comes up with a computational model to analyze the accented speech properties in both segmental (short-term speech measurements on short-segment or phoneme level) and suprasegmental (long-term speech measurements on word, long-segment, or sentence level) feature space. The benefit of using a computational model is that it enables quantitative analysis of L1's effect on accent in terms of different phonological properties. The core parts of this computational model are feature extraction schemes to extract pronunciation and prosody representation of accented speech based on existing techniques in speech processing field. Correlation analysis on both segmental and suprasegmental feature space is conducted to look into the relationship between acoustic measurements related to L1s and perceived accentedness across several L1s. Multiple regression analysis is employed to investigate how the L1's effect impacts the perception of foreign accent, and how accented speech produced by speakers from different L1s behaves distinctly on segmental and suprasegmental feature spaces. Results unveil the potential application of the methodology in this study to provide quantitative analysis of accented speech, and extend current studies in L2 speech learning theory to large scale. Practically, this study further shows that the computational model proposed in this study can benefit automatic accentedness evaluation system by adding features related to speakers' L1s.Dissertation/ThesisDoctoral Dissertation Speech and Hearing Science 201
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Deep Learning for Automatic Assessment and Feedback of Spoken English
Growing global demand for learning a second language (L2), particularly English, has led to
considerable interest in automatic spoken language assessment, whether for use in computerassisted language learning (CALL) tools or for grading candidates for formal qualifications.
This thesis presents research conducted into the automatic assessment of spontaneous nonnative English speech, with a view to be able to provide meaningful feedback to learners. One
of the challenges in automatic spoken language assessment is giving candidates feedback on
particular aspects, or views, of their spoken language proficiency, in addition to the overall
holistic score normally provided. Another is detecting pronunciation and other types of errors
at the word or utterance level and feeding them back to the learner in a useful way.
It is usually difficult to obtain accurate training data with separate scores for different
views and, as examiners are often trained to give holistic grades, single-view scores can
suffer issues of consistency. Conversely, holistic scores are available for various standard
assessment tasks such as Linguaskill. An investigation is thus conducted into whether
assessment scores linked to particular views of the speaker’s ability can be obtained from
systems trained using only holistic scores.
End-to-end neural systems are designed with structures and forms of input tuned to single
views, specifically each of pronunciation, rhythm, intonation and text. By training each
system on large quantities of candidate data, individual-view information should be possible
to extract. The relationships between the predictions of each system are evaluated to examine
whether they are, in fact, extracting different information about the speaker. Three methods
of combining the systems to predict holistic score are investigated, namely averaging their
predictions and concatenating and attending over their intermediate representations. The
combined graders are compared to each other and to baseline approaches.
The tasks of error detection and error tendency diagnosis become particularly challenging
when the speech in question is spontaneous and particularly given the challenges posed by
the inconsistency of human annotation of pronunciation errors. An approach to these tasks is
presented by distinguishing between lexical errors, wherein the speaker does not know how a
particular word is pronounced, and accent errors, wherein the candidate’s speech exhibits
consistent patterns of phone substitution, deletion and insertion. Three annotated corpora
x
of non-native English speech by speakers of multiple L1s are analysed, the consistency of
human annotation investigated and a method presented for detecting individual accent and
lexical errors and diagnosing accent error tendencies at the speaker level
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