Speech Rhythm-Based Speaker Embeddings Extraction from Phonemes and
  Phoneme Duration for Multi-Speaker Speech Synthesis
Kenichi Fujita Atsushi Ando Yusuke Ijima
This paper proposes a speech rhythm-based method for speaker embeddings to
model phoneme duration using a few utterances by the target speaker. Speech
rhythm is one of the essential factors among speaker characteristics, along
with acoustic features such as F0, for reproducing individual utterances in
speech synthesis. A novel feature of the proposed method is the rhythm-based
embeddings extracted from phonemes and their durations, which are known to be
related to speaking rhythm. They are extracted with a speaker identification
model similar to the conventional spectral feature-based one. We conducted
three experiments, speaker embeddings generation, speech synthesis with
generated embeddings, and embedding space analysis, to evaluate the
performance. The proposed method demonstrated a moderate speaker identification
performance (15.2% EER), even with only phonemes and their duration
information. The objective and subjective evaluation results demonstrated that
the proposed method can synthesize speech with speech rhythm closer to the
target speaker than the conventional method. We also visualized the embeddings
to evaluate the relationship between the distance of the embeddings and the
perceptual similarity. The visualization of the embedding space and the
relation analysis between the closeness indicated that the distribution of
embeddings reflects the subjective and objective similarity.