Speech Quality Evaluation Using Latent Clustering and Masked Prediction
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Solution Overview
Problem
Conventional quality evaluations of synthesized speech rely heavily on subjective metrics like Mean Opinion Score (MOS) and require large-scale speech-MOS pair datasets, limiting the development of effective objective evaluation methods.
Innovation Solution
An unsupervised learning-based method using anomaly detection to evaluate speech quality by extracting latent representations, clustering them, and calculating evaluation scores based on the difference between centroid and predicted index sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If supervised learning-based evaluation methods are used to estimate speech quality using MOS scores, then objective evaluation capability is improved, but large-scale speech-MOS pair datasets are required which increases data requirements and evaluation complexity
Solution Approach 1:
The patent replaces supervised learning-based MOS score estimation with an unsupervised anomaly detection approach. Instead of training models on large-scale speech-MOS pair datasets, the method uses normal speech data to train an autoencoder model that learns the distribution of normal speech. The quality evaluation is then performed by detecting anomalies between synthesized speech and the learned normal distribution, eliminating the need for large labeled datasets while maintaining objective evaluation capability.
Solution Approach 2:
The patent implements self-service by using the speech data itself to train the evaluation model. The autoencoder is trained solely on normal speech data without requiring external MOS labels. The model then uses its own learned representation to evaluate synthesized speech quality by measuring reconstruction errors, making the system self-sufficient and independent of large-scale annotated datasets.
2Measurement precision
If subjective metrics like Mean Opinion Score are used for quality evaluation, then human perception correlation is improved, but evaluation efficiency and objectivity deteriorate due to requiring multiple evaluators and manual scoring
Solution Approach 1:
The patent substitutes manual subjective evaluation with an automated unsupervised learning system. The autoencoder model processes speech data automatically, computing reconstruction errors as quality metrics without requiring human evaluators. This maintains objective measurement while dramatically improving evaluation efficiency and scalability.
Solution Approach 2:
The patent introduces latent representations as an intermediary between raw speech data and quality evaluation. The autoencoder compresses speech into latent space, and quality is assessed through reconstruction error in this intermediate representation. This intermediary mechanism enables automated objective evaluation that correlates with human perception without requiring direct human involvement in the evaluation process.
3Productivity
If unsupervised learning with anomaly detection is used to evaluate speech quality, then data requirements are reduced and evaluation efficiency is improved, but the complexity of processing latent representations and computing reconstruction errors increases
Solution Approach 1:
The patent applies preliminary action by pre-training the autoencoder model on normal speech data to learn the distribution of normal speech patterns. This preprocessing step creates a reference model that can quickly evaluate synthesized speech without requiring complex real-time analysis. The latent space representation and reconstruction mechanism are established in advance, simplifying the actual quality evaluation process.
Data Source
AI summary
In an embodiment a method for evaluating speech quality includes receiving, by a computing device, synthesized speech comprising one or more frames, determining, by the computing device, a latent representation corresponding to each frame, clustering, by the computing device, each latent representation and then mapping a center point of each cluster to an index to determine a centroid index sequence, determining, by the computing device, an embedding sequence by replacing each index of the centroid index sequence with an embedding corresponding to each index, and then masking one or more of embeddings, determining, by the computing device, a predicted index sequence that reconstructs a masked embedding based on a masked embedding sequence, and determining, by the computing device, an evaluation score based on a difference between the centroid index sequence and the predicted index sequence.


