4.1. Measuring Duration – Phonetics and Phonology

Once the sound file is open in the Editor window, you can read the total duration easily from the duration bar, but if you want to know the duration of your selected part, you can follow the following steps (Styler, 2012:13):

Select the portion of the file you’d like to measure with the cursor
Read the duration of the selection (in seconds) from the duration bar along the bottom of the Editor window
"Editor" → "Query" → "Get selection length" and read your selection in the "Info" window

If you’d like to know the duration of an entire file, just select the file in the Objects window and select "Objects" → "Query" → "Query Time Domain" → "Get Total Duration".

"Voice Onset Time" (VOT) is the time between when the stop is released and when the voicing of the following vowel begins. Measuring this time, which can be positive (say, for the English voiceless aspirated stop [t^h]), around zero (for the English "voiced" stop /d/, or, more commonly, the voiceless unaspirated [t]), or negative (for fully voiced stops, where voicing starts before the stop is released, as found in most non-English languages). Languages classify their stops largely based on voice onset time, and it’s an excellent way of proving the "voiced/voiceless" phonological distinction.

Measuring voice onset time (VOT) is very easy to do in Praat, as it’s just a duration measurement between two set points, the release of the stop and the start of voicing.

Find the stop release
Find the start of voicing
Select the span between these two points
Read the duration of the selection (in seconds) from the duration bar along the bottom of the Editor window

If the start of voicing came before the stop release, the VOT is negative. Otherwise, the VOT is positive. In general, voiced sounds (in languages other than English) will have a VOT which is negative. Voiceless unaspirated sounds will have a VOT which is around 0, and aspirated sounds will have a positive VOT (Styler, 2012:14)。

As Heike (1987) observed, linking can occur in English between two consonants, between a consonant and a vowel, or between two vowels.

Consonant-to-consonant (CC) linking occurs when the final consonant of the former word and the initial consonant of the latter word are identical, (e.g., “that time”), only one consonant is manifest and may be slightly prolonged.
Consonant-to-vowel (CV) linking (e.g. “kind of”) involves the assignment of the final consonant of a word to the following, vowel-initial syllable.
Vowel-to-vowel (VV) linking (e.g. “say it”) occurs when a word-final tense vowel is followed by a word-initial vowel. This kind of linking often involves glide attraction.

We can decide whether there is linking by measuring the duration of CC, CV, and VV in Praat.

Pause is defined as "any interval of the oscillographic trace where the amplitude is indistinguishable from that of the background noise" (Duez, 1982, p.13). Intensity can be considered the acoustic cue to measure pause (Chen, 2005). Pauses could be analyzed by measuring pause duration, pause distribution, and pause location. As a common practice, only those pauses greater than 100 ms, the cut-off for pauses (Griffths, 1991), were considered to be a "pause". Therefore, we can decide whether there is a pause by measuring the duration between two adjacent words.