I am trying to segment some connected speech in Praat, and want to get the boundaries between phonemes as accurate as possible. I am finding that in many cases, one sound blends into another and it's hard to say where the dividing line is.
Praat obviously provides a good few clues, but I'm not sure how much weight I should attach to them. Looking at the word /cə/ for example:
The waveform has a very clear change in shape near the beginning, so the obvious starting point is to treat the first shape as /c/ and the rest as /ə/ - but if I do that the bit that is supposed to be /ə/ sounds like /də/.
At a slightly later point, I would say that the formants settle (they are a bit wobbly throughout) - but again a boundary there gives me /də/.
Slightly later still, the first vocal pulse appears. I am not sure how far I can trust the vocal pulses shown in Praat, but in any case I still get the /də/ if I put the boundary here.
If I move the boundary so that the second segment sounds like /ə/, the end of the bit that is supposed to be /c/ is audibly voiced.
Clearly there are a number of things going on in this transition and they don't all happen simultaneously (or instantaneously).
Is there a principled basis for choosing one of these points - or perhaps another one altogether - as the boundary between consonant and vowel?