Hi, I have just come across your question. I appreciate this may no longer be timely but I am adding a couple pointers in case they can help others.
For isolating or segmenting speech in low-noise recordings, the function detectSpeech should work just fine. This will return start and stop times of all signal regions where speech is detected, but no text "transcription" of the actual speech content.
Based on that info you then can label each section of your recording as voiced or unvoiced.
