ISCA Archive Interspeech 2014
ISCA Archive Interspeech 2014

BUT 2014 Babel system: analysis of adaptation in NN based systems

Martin Karafiát, František Grézl, Karel Veselý, Mirko Hannemann, Igor Szőke, Jan Černocký

Features based on a hierarchy of neural networks with compressive layers — Stacked Bottle-Neck (SBN) features — were recently shown to provide excellent performance in LVCSR systems. This paper summarizes several techniques investigated in our work towards Babel 2014 evaluations: (1) using several versions of fundamental frequency (F0) estimates, (2) semi-supervised training on un-transcribed data and mainly (3) adapting the NN structure at different levels. They are tested on three 2014 Babel languages with full GMM- and DNN-based systems. Separately and in combination, they are shown to outperform the baselines and confirm the usefulness of bottle-neck features in current ASR systems.