"The vowel landmarks are the places in the signal where there is a maximum in amplitude in the range of the first formant frequency. These places are usually where the first formant frequency is maximally high." (Stevens, 1998)
Implications:
" ... the time between the landmarks is rarely shorter than 120 ms, and, except when there is a pause, is rarely longer than about 350 ms in running speech." (ibid.)
Implications: