Automatic Phonetic Transcription in Two Steps: Forced Alignment and Burst Detection

In the last decade, there was a growing interest in conversational speech in the fields of human and automatic speech recognition. Whereas for the varieties spoken in Germany, both resources and tools are numerous, for Austrian German only recently the first corpus of read and conversational speech was collected. In the current paper, we present automatic methods to phonetically transcribe and segment (read and) conversational Austrian German. For this purpose, we developed an automatic two-step transcription procedure: In the first step, broad phonetic transcriptions are created by means of a forced alignment and a lexicon with multiple pronunciation variants per word. In the second step, plosives are annotated on the sub-phonemic level: an automatic burst detector automatically determines whether a burst exists and where it is located. Our preliminary results show that the forced alignment based approach reaches accuracies in the range of what has been reported for the inter-transcriber agreement for conversational speech. Furthermore, our burst detector outperforms previous tools with accuracies between 98% and 74% for the different conditions in read speech, and between 82% and 52% for conversational speech.