Speaking Speed Control of End-to-End Speech Synthesis using Sentence-Level Conditioning
This addresses the problem of unnatural speech synthesis at varied speeds for TTS applications, though it is incremental by improving upon existing duration control methods.
The paper tackled controlling speaking speed in end-to-end text-to-speech synthesis by using sentence-level conditioning, resulting in more natural speech generation, especially for slow-speed speech, as shown in listening tests.
This paper proposes a controllable end-to-end text-to-speech (TTS) system to control the speaking speed (speed-controllable TTS; SCTTS) of synthesized speech with sentence-level speaking-rate value as an additional input. The speaking-rate value, the ratio of the number of input phonemes to the length of input speech, is adopted in the proposed system to control the speaking speed. Furthermore, the proposed SCTTS system can control the speaking speed while retaining other speech attributes, such as the pitch, by adopting the global style token-based style encoder. The proposed SCTTS does not require any additional well-trained model or an external speech database to extract phoneme-level duration information and can be trained in an end-to-end manner. In addition, our listening tests on fast-, normal-, and slow-speed speech showed that the SCTTS can generate more natural speech than other phoneme duration control approaches which increase or decrease duration at the same rate for the entire sentence, especially in the case of slow-speed speech.