Vowel formant dispersion in apraxia of speech and aphasia: repeated elicitation versus spontaneous speech.
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1
Department of Communication Sciences and Disorders, Arnold School of Public Health, University of South Carolina, United States
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2
University of South Carolina, United States
In a recent study, Den Ouden et al. (2018) showed that magnitude of vowel formant dispersion was a consistent predictor of presence and severity of apraxia of speech (AOS) in stroke survivors. Vowel formants are the resonant frequencies of the vocal tract that resonate the loudest and are seen as peaks in a spectrum, by which vowels are acoustically distinguished from one another. Speakers with AOS (mostly with concomitant aphasia) showed high levels of variance in their vowel production, particularly in the second formant, whereas the vowel productions by speakers with aphasia (without AOS) were not different from productions by stroke survivors without language or speech deficits. This finding supports a classically hypothesized selection versus control distinction between aphasia and AOS, extending it to a measurable difference at the vowel level, where previous research had either focused on consonant production or suggested that vowel articulation was less impaired than consonant articulation in AOS.
A previous study by Jacks et al. (2010) did not yield differences in formant variance between speakers with AOS and unimpaired control speakers. Within-subject formant variability of speakers with AOS was comparable to that of unimpaired speakers, forcing the conclusion that production of monophthongal vowels in words may be stable in AOS. It is of interest to investigate what may account for the different results in the two studies. One difference is that Jacks et al. used repetitive elicitation of vowels in a /hVC/ context (heat, head, hoot, etc.), read from screen, whereas Den Ouden et al. extracted vowels from continuous spontaneous speech. Repetitive elicitation may have had a stabilizing effect on speech production Jacks et al.’s participants, which may have important clinical implications for treatment. The present study directly tests vowel formant dispersion in aphasic an apraxic speakers under conditions of repeated single-word elicitation versus continuous descriptive speech.
Methods. We are testing (1) 12 speakers with aphasia, without AOS, (2) 12 speakers with AOS, and (3) 12 age-matched healthy control speakers. Aphasia and AOS severity are assessed with the Western Aphasia Battery – Revised (Kertesz, 2007) and the AOS rating scale (Strand et al., 2014). For spontaneous speech, participants look at paintings (Brueghel, Mailer) and are asked to describe what is happening in the picture. The repeated-elicitation task uses the same stimuli and design as that used by Jacks et al. (2010). All samples are transcribed in Praat (Boersma & Weenink, 2001), and a dedicated script is then used to extract vowel-formant values (Lennes, 2003). Within-subject standard deviations are calculated for the first three formants, for comparison between groups and elicitation conditions in a 3x2 ANOVA.
Results. At present, we have tested all control participants, and half of the speakers in the two other groups. Results will be presented on differences in vowel formant stability between repeated-elicitation and spontaneous-speech conditions, as well as between the three groups of speakers.
References
Boersma, P., & Weenink, D. (2001). Praat: doing phonetics by computer . Retrieved from PRAAT: http://www.fon.hum.uva.nl/praat/
Den Ouden, D.B., Galkina, E., Basilakos, A. & Fridriksson, J. (2018) Vowel formant dispersion reflects severity of Apraxia of Speech. Aphasiology, 32:8, 902-921.
Jacks, A., Mathes, K. A., & Marquardt, T. P. (2010). Vowel Acoustics in Adults with Apraxia of Speech. Journal of Speech, Language, and Hearing Research, 61-74.
Kertesz, A. (2007). Western Aphasia Battery - Revised. San Antonio, TX.: Pearson.
Lennes, M. (2003). Collect_formant_data_from_files.praat [Praat script], from http://www.helsinki.fi/~lennes/praat-scripts/public
Strand, E. A., Duffy, J. R., Clark, H. M., & Josephs, K. (2014). The Apraxia of Speech Rating Scale: a tool for diagnosis and description of apraxia of speech. Journal of Communication Disorders, 51, 43-50.
Keywords:
apraxia of speech (AOS),
speech production,
Vowel acoustics,
diagnostic criteria,
Acoustic Analyses
Conference:
Academy of Aphasia 57th Annual Meeting, Macau, Macao, SAR China, 27 Oct - 29 Oct, 2019.
Presentation Type:
Poster presentation
Topic:
Not eligible for student award
Citation:
Den Ouden
DB,
Del Valle
G,
Altpeter
H and
Galkina
E
(2019). Vowel formant dispersion in apraxia of speech and aphasia: repeated elicitation versus spontaneous speech..
Front. Hum. Neurosci.
Conference Abstract:
Academy of Aphasia 57th Annual Meeting.
doi: 10.3389/conf.fnhum.2019.01.00079
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Received:
06 May 2019;
Published Online:
09 Oct 2019.
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Correspondence:
Dr. Dirk B Den Ouden, Department of Communication Sciences and Disorders, Arnold School of Public Health, University of South Carolina, Columbia, South Carolina, 29208, United States, denouden@sc.edu