Scaling and bias codes for modeling speaker-adaptive DNN-based speech synthesis systems

ABSTRACT Most neural-network based speaker-adaptive acoustic models for speech synthesis can be categorized into either layer-based or input-code approaches. Although both approaches have their own pros and cons, most existing works on speaker adaptation focus on improving one or the other. In this paper, after we first systematically overview the common principles of neural-network based speaker-adaptive models, we show that these approaches can be represented in a unified framework and can be generalized further. More specifically, we introduce the use of scaling and bias codes as generalized means for speaker-adaptive transformation. By utilizing these codes, we can create a more efficient factorized speaker-adaptive model and capture advantages of both approaches while reducing their disadvantages. The experiments show that the proposed method can improve the performance of speaker adaptation compared with speaker adaptation based on the conventional input code. Index Terms -- speech synthesis, speaker adaptation, neural network, factorization, speaker code 1. INTRODUCTION Recent speaker-dependent speech synthesis systems can generate high-quality reading speech indistinguishable from natural human speech when their training data is recorded in a quality-controlled condition and have sufficient amount of data [1].