We propose a self-supervised representation learning model for the task of
unsupervised phoneme boundary detection. The model is a convolutional neural
network that operates directly on the raw waveform. It is optimized to identify
spectral changes in the signal using the Noise-Contrastive Estimation
principle. At test time, a peak detection algorithm is applied over the model
outputs to produce the final boundaries. As such, the proposed model is trained
in a fully unsupervised manner with no manual annotations in the form of target
boundaries nor phonetic transcriptions. We compare the proposed approach to
several unsupervised baselines using both TIMIT and Buckeye corpora. Results
suggest that our approach surpasses the baseline models and reaches
state-of-the-art performance on both data sets. Furthermore, we experimented
with expanding the training set with additional examples from the Librispeech
corpus. We evaluated the resulting model on distributions and languages that
were not seen during the training phase (English, Hebrew and German) and showed
that utilizing additional untranscribed data is beneficial for model
performance.

本研究提出了一种自监督表示学习模型，用于无监督音素边界检测，该模型是一个卷积神经网络，直接在原始波形上进行操作，利用噪声对比估计原则优化识别信号中的频谱变化，并在测试时间通过峰值检测算法应用于模型输出以产生最终边界。结果表明，该方法优于基线模型，并在两个数据集上达到了最先进的性能，同时使用额外未转录数据有助于模型表现。