Raw-x-vector: Multi-scale Time Domain Speaker Embedding Network
State-of-the-art text-independent speaker verification systems typically use cepstral features or filter bank energies of speech utterances as input features. With the ability of deep neural networks to learn representations from raw data, recent studies attempted to extract speaker embeddings directly from raw waveforms and showed competitive results. In this paper, we propose a new speaker embedding called raw-x-vector for speaker verification in the time domain, combining a multi-scale waveform encoder and an x-vector network architecture. We show that the proposed approach outperforms existing raw-waveform-based speaker verification systems by a large margin. We also show that the proposed multi-scale encoder improves over single-scale encoders for both the proposed system and another state-of-the-art raw-waveform-based speaker verification systems. A further analysis of the learned filters shows that the multi-scale encoder focuses on different frequency bands at its different scales while resulting in a more flat overall frequency response than any of the single-scale counterparts.
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