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Front matter  /  Abbreviations

List of Abbreviations and Notations

Acronyms, mathematical notations, and conventions used throughout the present thesis. Entries are grouped first by acronyms in alphabetical order, then by mathematical notation.

Section A

Acronyms

AbbreviationMeaning
3DDoctoral School "Dynamiques du Developpement Durable", University of Toamasina
APAAmerican Psychological Association (citation style)
APIApplication Programming Interface
ARAutoregressive (decoder family)
ASRAutomatic Speech Recognition
AUCArea Under the Curve
BLEUBilingual Evaluation Understudy (translation metric)
BPEByte-Pair Encoding
CERCharacter Error Rate
CTCConnectionist Temporal Classification
CVCommon Voice (Mozilla multilingual speech corpus)
CV-MGCommon Voice, Malagasy subset
DNNDeep Neural Network
DOIDigital Object Identifier
ECEExpected Calibration Error
EDTMEcole Doctorale Themes Multiples (here EDTM 3D)
ELBOEvidence Lower Bound
EMExpectation-Maximization algorithm
F1Harmonic mean of precision and recall
FLEURSFew-shot Learning Evaluation of Universal Representations of Speech
FLEURS-MGFLEURS benchmark, Malagasy subset
FLOPSFloating-Point Operations per Second
FRFrench (code-switching language tag)
GMMGaussian Mixture Model
GPUGraphics Processing Unit
HMMHidden Markov Model
IMRaDIntroduction, Materials and Methods, Results, Discussion
IPAInternational Phonetic Alphabet
ITPIterative Pseudo-Labeling
JSJensen-Shannon (divergence)
JSONJavaScript Object Notation
KLKullback-Leibler (divergence)
LASListen, Attend and Spell
LF-MMILattice-Free Maximum Mutual Information
LLMLarge Language Model
LMLanguage Model
LoRALow-Rank Adaptation
MAPMaximum A Posteriori
MFCCMel-Frequency Cepstral Coefficients
MGMalagasy (language code)
MLEMaximum Likelihood Estimation
MMIMaximum Mutual Information
MMSMassively Multilingual Speech
MoEMixture of Experts
NISTNational Institute of Standards and Technology
NLPNatural Language Processing
NMTNeural Machine Translation
OWSMOpen Whisper-style Speech Model
PLPPerceptual Linear Prediction
RNNRecurrent Neural Network
RNN-TRecurrent Neural Network Transducer
ROCReceiver Operating Characteristic
SIGULACL Special Interest Group on Under-resourced Languages
SI-SNRScale-Invariant Signal-to-Noise Ratio
slimIPLSlim Iterative Pseudo-Labeling
SNRSignal-to-Noise Ratio
SSLSelf-Supervised Learning
TASLPIEEE/ACM Transactions on Audio, Speech and Language Processing
TDNNTime-Delay Neural Network
TDNN-FFactorized Time-Delay Neural Network
TPUTensor Processing Unit
USMUniversal Speech Model
VADVoice Activity Detection
VAEVariational Autoencoder
WavLMSpeech pre-training framework with denoising
WERWord Error Rate
WFSTWeighted Finite-State Transducer
XLS-RCross-Lingual Speech Representation (large-scale)
XLSRCross-Lingual Speech Representation (initial release)
Section B

Mathematical notation

SymbolMeaning
\(x\)Acoustic input (waveform or feature sequence)
\(y\)Transcript (sequence of characters, sub-words or tokens)
\(W\)Word sequence (classical notation)
\(X\)Acoustic feature sequence (classical notation)
\(P(W \mid X)\)Posterior probability of word sequence given acoustic features
\(P(X \mid W)\)Acoustic likelihood
\(P(W)\)Language-model prior over word sequences
\(q(y \mid x)\)Variational approximate posterior
\(q_W,\ q_M,\ q_B\)Posteriors of the three teachers (Whisper, MMS, Wav2Vec2-BERT)
\(p_\theta\)Model with parameters \(\theta\)
\(\theta\)Model parameters
\(\alpha,\ \beta\)Mixture weights (language-model and typological prior)
\(\lambda\)Regularization weight
\(P_{\mathrm{typ}}(y)\)Typological (Austronesian family) prior over transcripts
\(d,\ r,\ c\)Latent dialect, register, and code-switching variables
\(D_{\mathrm{sup}},\ D_{\mathrm{unsup}}\)Supervised and unsupervised data subsets
\(\mathrm{KL}(q \,\|\, p)\)Kullback-Leibler divergence from p to q
\(\mathrm{JS}(p, q)\)Jensen-Shannon divergence
\(\mathbb{E}_q[\,\cdot\,]\)Expectation under distribution q
\(\mathcal{L}_{\mathrm{CTC}}\)Connectionist Temporal Classification loss
\(\mathcal{L}_{\mathrm{RNNT}}\)RNN-Transducer loss
\(\mathcal{L}_{\mathrm{att}}\)Attention-based cross-entropy loss
\(\mathcal{L}_{\mathrm{ELBO}}\)Evidence Lower Bound objective
\(r(\cdot)\)Routing function (Component 3.1)
\(C\)Constraint set of the constrained variational EM
\(R(\theta)\)Regularization term on parameters
\(T\)Temperature parameter in calibration / softmax
\(\mathrm{ECE}_n\)Expected Calibration Error with \(n\) confidence bins
\(H(p)\)Shannon entropy of distribution p