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3-way contrasts of voicing

Korean is particularly interesting because here it is even clearer than in Thai that the differences cannot be explained just by differences in laryngeal-oral timing.

The three voicing categories can be described as follows:
  1. Voiceless aspirated.
  2. Voiceless unaspirated, or weakly aspirated in initial position,
    often voiced intervocalically; frequently referred to as "lenis".
  3. Voiceless aspirated; "fortis" (also referred to as "forced"),
    particularly characteristic of these stops is the abrupt onset of phonation
    after closure release ("stiff voice", Ladefoged & Maddieson, 2008, p. 56),
    i.e. it can be assumed that there is much higher tension in the vocal folds
    at voice onset in this category compared to the lenis category.

Examples from IPA

Please note that p*, t*, etc. stand for the unaspirated fortis plosives (Ladefoged & Maddieson 2008, p. 56), which in standard IPA are symbolized simply as p, t, etc.

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Examples from our own data at IPS

For this speaker, there is actually a fairly consistent difference in VOT between the lenis and the fortis stops (longer VOT for the lenis stops). However, the more abrupt onset of the higher harmonics in the fortis category illustrates well the difference in voice quality at vowel onset following these two sounds. In addition, a consistent difference in fundamental frequency at voicing onset is also found (higher for the fortis category). Findings of this kind have also been reported by Dart (1987).

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Additional Analyses of the Korean data from IPS

  1. Measurements of VOT for a large number of tokens show that the lenis stop indeed lies on average between the fortis and aspirated stops, but that individual tokens can be very close to both these categories.
    Click here to see a plot of the VOT values. VOT is on the y-axis, the x-axis simply arranges the tokens in the order they occurred in during the experiment.

  2. For this speaker, we also measured intra-oral air-pressure. Despite its name, there were no clear differences between the fortis stop and the other two categories in terms of peak air-pressure during consonantal closure. It can be seen in the sonagrams, however, that the duration of closure is clearly longer for the fortis stop than for the lenis stop.

  3. A combination of voice quality and fundamental frequency (measured at the onset of phonation) also distinguishes the three categories well. Thus even when VOT is ambiguous, adequate differentiation is possible.
    Click here to see a plot of fundamental frequency (y-axis) plotted against the closed quotient (x-axis). The color coding is the same as in the VOT plot above.
    The closed quotient, which was measured from the electroglottographic waveform, expresses the duration of glottal closure as a proportion (in percent) of the duration of a complete vibratory cycle during phonation. Lower values indicate more forceful glottal closure and should be accompanied by stronger upper harmonics in the specturm (refer back to the sonagrams).


Audio Source:
Illustrations of the IPA.
Institute of Phonetics and Speech Processing, LMU Munich.

Ladefoged, P. / Maddieson, I. (2008): The Sounds of the World's Languages. Malden, MA: Blackwell.