Investigating Gated Recurrent Networks for Speech Synthesis
Table 2: Objective measures. MCD: Mel-Cepstral Distortion. BAP: distortion of band aperiodicities. F0 RMSE is calculated on a linear scale. V/UV: voiced/unvoiced error. Note that the number of parameters listed is for the recurrent layer only and does not include the bottom three feed-forward layers, which are the same size across all systems. The generation time is to generate all the 142 utterances in both development and testing sets.
['[EMPTY]', 'MCD', 'BAP', 'F0 RMSE', 'V/UV', '# parameters', 'generation']
Even though objective measures might not always correlate with human perception, they offer a way to tune the systems and roughly predict model performance. Compared to LSTM, NIG, NOG and NPH all achieve similar objective distortion, with considerably fewer parameters and lower generation time: the input gate, output gate and peep-hole connections are not necessary. The NFG system increases distortion considerably: the forget gate is important. The NFG system achieves only a 20.3% preference score when paired against the LSTM which is preferred 74.3% of the time.