Phonological and articulatory disturbances in a case of primary progressive aphasia

Phonological processing abilities of a right-handed female (B.F.) with a primary progressive aphasia (PPA) is reported. Phonemic paraphasias and articulatory errors characterized speech production. On first examination her expressive deficit suggested an apraxia of speech in the absence of any other language or cognitive deficits. However, systematic assessment of her speech showed many errors were related to poor selection and sequencinig of phonemes. Auditory discrimination was comparable to that of four normal young adults. Error monitoring was poor. B.F. had difficulty monitoring her own speech production errors as well as those of others, accurately identifying errors 50% of the time. B.F. failed to identify articulatory errors (prolongations and repetitions) but not phonological errors (transpositions and substitutions). The data suggest that articulatory disturbances might cause a shift in a speaker's perceptions of accuracy of production. On the other hand, these phonetic level errors may be ignored because the intended articulatory gestures are recovered even when the acoustic signal is distorted, allowing the application of appropriate phonetic categories. Motoric and linguistic mechanisms may underlie not only the misarticulations in patients with PPA but also patients with apraxia of speech.