Visual examples of speech behaviors that are associated with apraxia of speech in the nonfluent variant (A2, B2) rather than the logopenic variant (A1, B1).
In A1 and A2, the blue vertical lines mark the boundaries of the 2 vowels used to measure lexical stress. In B1 and B2, the black line shows vocal intensity (i.e. loudness) and the blue line fundamental frequency (i.e. vocal pitch, uncorrected) during speech; The intensity contour falls and the pitch contour breaks when the voice is silent during unvoiced sounds (e.g. ‘t’, ‘f’) or during pauses in speech. A1: Normal speech rate and lexical stress on polysyllabic words (here, the first ‘a’ vowel in ‘banana’ is very brief and much shorter than the second vowel) and no phonetic distortions; Total sample length 900 msec. A2: Slow speech rate, equal lexical stress on polysyllabic words (here, the two ‘a’ vowels in banana are of similar and longer duration, giving the perception of equal stress), and phonetic distortion on the final ‘n’ (closure of the velopharyngeal port is mistimed, blocking the nasal airflow before the tongue tip drops away from the palate, creating a sound similar to ‘d’); Total sample length 900 msec. B1: Normal speech rate and smooth transitions between syllables; Total sample length 1500 msec, 7 syllables. B2: Slowed speech rate and syllable segregation (here, the transitions between ‘-bout’ and ‘my’ and between ‘my’ and ‘grand’ are longer and more distinct in the nonfluent case), as well as distortion/substitution where the ‘f’ sound is perceived as ‘f’ but is momentarily voiced (short segment of blue line) similar to a ‘v’; Total sample length 1500 msec, 5 syllables.
More »