Whilst we're all familiar with voicing on an intuitive and/or phonological level, the actual acoustic phonetics are somewhat less intuitive to many of us.
The main way of formalising this intuitive notion of voicing in acoustic phonetics that I'm aware of is Voice Onset Time (VOT).
This is typically defined as the difference in time between the release of the consonant and the start of voicing.
- A negative VOT means the voicing started before the release of the consonant and corresponds to a voiced consonant.
- A VOT close to 0 means the voicing starts as the consonant is released and correspond to a tenuis voiceless consonant.
- A positive VOT means the voicing starts only a while after the release of the consonant and corresponds to an aspirate consonant.
This definition works perfectly well for consonants in the syllable onset (although there are potentially issues post-pausa), but it's extremely unclear how to apply this in the syllable coda (especially pre-pausa). It also doesn't seem to have a way to describe preaspiration which according to Silverman, 2003, On the rarity of pre-aspirated stops can occur word and utterance initially in Huautla Mazatec (although no other examples seem to be known, so if this is mistaken then this issue is connected to the preceding one).
The obvious equivalent for coda consonants would be to look at the Voice Cessation Time (i.e. the time between the start of occlusion in the consonant and the end of the voicing) which would seem to give:
- A negative VCT would then be preaspirated.
- A VCT close to 0 would be tenuis.
- A positive VCT would be voiced.
This seems a plausible extension, but doesn't seem to allow for final (post)aspirates, something that's frequently described.
My question then is: what's accousatically going on with preaspirates (especially word and utterance initially, if such exist), and relatedly, what's going on acoustically with (post)-aspirates word and utterance finally?