Wild, A., Vorperian, H.K., Kent, R. D., Bolt, D.M. & Austin, D. (In press, 2017). Single-word Speech Intelligibility in Children and Adults with Down Syndrome. American Journal of Speech-Language Pathology.
Fisher, E., Austin, D., Werner, H., Chuang, Y.J., Bersu, E. & Vorperian, H.K. (2016). Hyoid bone fusion and bone density across the lifespan: prediction of age and sex. Forensic Science, Medicine and Pathology. doi: 10.1007/s12024-016-9769-x. PMCID: PMC4859847.
Wang, Y., Chung, M.K. & Vorperian, H.K. (2015). Composite growth model applied to human oral and pharyngeal structures and identifying the contribution of growth types. Statistical Methods in Medical Research. doi: 10.1177/0962280213508849. PMCID: PMC4183732.
Summary/Significance: The vocal tract structures (oral and pharyngeal) are housed in the craniofacial complex where the cranium/brain follows a distinct neural growth pattern, and the face follows a distinct somatic or skeletal growth pattern. Existing parametric growth models are limited in that they are mainly focus on modeling one specific type of growth pattern. In this study, we propose a novel composite growth model using neural and somatic baseline curves to fit the combined growth pattern of specific vocal tract structures. This method is also able to determine the overall percent contribution of each growth type.
Chung, M.K., Qiu, A., Seo, S. & Vorperian, H.K. (2015). Unified heat kernel regression for diffusion, kernel smoothing and wavelets on manifolds and its application to mandible growth modeling in CT images. Medical Image Analysis, 22(1), 63-76. doi: 10.1016/j.media.2015.02.003. PMCID: PMC4405438.
Summary/Significance: This study presents a novel kernel regression framework for smoothing noisy mandible surface data using the Laplace–Beltrami eigenfunctions. The numerical implementation is further validated on a unit sphere using spherical harmonics with known ground truth. The method is applied to characterize the localized growth pattern of mandible surfaces obtained in CT images between ages 0 and 20 by regressing the length of displacement vectors with respect to a surface template. Findings support the downward and forward growth trend of the mandible as described in the literature, and further depict mandibular growth in all planes.
Cotter, M.M., Whyms, B.J., Kelly, M.P., Doherty, B.M., Gentry, L.R., Bersu, E.T. & Vorperian, H.K. (2015). Hyoid bone development: An assessment of optimal CT scanner parameters and 3D volume rendering techniques. The Anatomical Record. doi: 10.1002/ar.23157. PMCID: PMC4503494.
Summary/Significance: The hyoid bone and the mandible provide the skeletal framework for the tongue that is critical for speech production. Much like the Whyms et al. (2013) study listed above, this study systematically assesses the optimal CT scanner and rendering parameters to accurately measure the hyoid bone. It also provides pilot data from in vivo scans documenting the feasibility of using retrospective clinical imaging studies to quantify the growth and development of the hyoid bone.
Derdemezis, E., Vorperian, H.K., Kent, R.D., Fourakis, M., Reinicke, E.L. & Bolt, D.M. (2015). Optimizing vowel formant measurements in four acoustic analysis systems for diverse speaker groups. American Journal of Speech-Language Pathology, Epub 2015 Oct 23. doi: 10.1044/2015_AJSLP-15-0020. PMCID: PMC5270637.
Kent, R.D., Kurtzweil, S.L., Fourakis, M., Kent, R.D., Tillman, K.T. & Austin, D. (2015). Nonspeech Oral Movements and Oral Motor Disorders: A Narrative Review. American Journal of Speech Language Pathology, 24, 763-789. doi: 10.1044/2015_AJSLP-14-0179. PMCID: PMC4698470.
Summary/Significance: The use of oral nonspeech tasks in speech-language pathology and related disciplines is highly controversial. Efforts to understand the relationships among speech and nonspeech behaviors are hindered by the lack of explicit and widely accepted definitions. This article offers definitions and a taxonomy of nonspeech tasks that should help to guide their clinical application and the selection of nonspeech control tasks in research on speech production.
Vorperian, H.K., Kurtzweil, S.L., Fourakis, M., Kent, R.D., Tillman, K.T. & Austin, D. (2015). Effect of body position on vocal tract acoustics: Acoustic pharyngometry and vowel formants. Journal of the Acoustical Society of America, 833-845. EPub 2015 Aug 17. doi: 10.1121/1.4926563. PMCID: PMC4545056.
Summary/Significance: This study examined the effect of body position on vocal tract acoustics to address the question of whether anatomic measurements from medical imaging studies (from the supine position) can be used to make inferences on speech (from the upright body position). Upright versus supine data of vowel acoustic measurements and anatomic measurements from acoustic pharyngometry were compared. Findings revealed that adult speakers compensate fairly well, but not completely, for changes in body position relative to the gravitational field. Thus data obtained from one body position can be generalized with caution to another body position.
Burris, C., Vorperian, H.K., Fourakis, M., Kent, R.D. & Bolt, D.M. (2014). Quantitative and descriptive comparison of four acoustic analysis systems: vowel measurements. Journal of Speech, Language, and Hearing Research, 57(1):26–45. doi: 10.1044/1092-4388(2013/12-0103). PMCID: PMC3972630.
Summary/Significance: This study examined the accuracy and comparability of four trademarked acoustic analysis software packages (AASPs): Praat, WaveSurfer, TF32, and CSL by using synthesized and natural vowels. Results indicate that Praat, WaveSurfer, and TF32 generate accurate and comparable data on vocal fundamental frequency and the first four formant frequencies for synthesized vowels and adult male natural vowels. However, the results were more variable by vowel for women and children, with some serious errors in formant frequencies. Bandwidth measurements were judged to be unreliable across all four systems. This report guides users in the selection and performance of acoustic analysis systems for speech.
Hosseinbor, A.P., Kim, W.H., Adluru, N., Acharya, A., Vorperian, H.K. & Chung, M.K. (2014). The 4D hyperspherical diffusion wavelet: a new method for the detection of localized anatomical variation. 17th International Conference on Medical Image Computing and Computer Assisted Intervention (MICCAI). Lecture Notes in Computer Science (LNCS), 8675:65-72. doi: 10.1007/978-3-319-10443-0_9. PMCID: PMC4317359.
Summary/Significance: A unified wavelet framework that links existing HyperSPHARM representation to the diffusion wavelet transform is presented. This new framework allows for the statistical inference of highly localized anatomic changes, as demonstrated in the first-ever developmental study on segmented hyoid bones between the ages birth to 20 years. Findings revealed localized growth spurts and sex differences in hyoid bone growth. Findings also revealed that the HyperSPHARM wavelet successfully picks up group-wise differences that are barely detectable using the existing SPHARM representation.
Kent, R.D. & Vorperian, H. K. (2013). Speech Impairment in Down Syndrome: A Review. Journal of Speech, Language, and Hearing Research, 56(1):178–210. doi: 10.1044/1092-4388(2012/12-0148). PMCID: PMC3584188.
Summary/Significance: This paper offers a thorough review of the literature covering studies on voice, speech sounds, fluency and prosody, and intelligibility in children and adults with Down syndrome for the purposes of informing clinical services and guiding future research. Summary highlights that in each of these areas, individuals with Down syndrome experience limitations that can seriously affect speech communication. The origin of these limitations appears to be multi-factorial, including craniofacial dysmorphologies, deficiencies in speech learning, and disturbances in speech motor control.
Whyms, B.J., Vorperian, H.K., Gentry, L.R., Schimek, E.M., Bersu, E.T. & Chung, M.K. (2013). The effect of CT scanner parameters and 3D volume rendering techniques on the accuracy of linear, angular, and volumetric measurements of the mandible. Oral Surgery, Oral Medicine, Oral Pathology, and Oral Radiology, 115(5):682–691. doi: 10.1016/j.oooo.2013.02.008. PMCID: PMC3633147.
Summary/Significance: This study systematically investigated the effect of CT scanner parameters on the accuracy of measurements from three-dimensional (3D) mandible renderings as compared to anatomic truth measurements. The range of acceptable parameters to confidently secure linear, angular and volumetric measurements increases the availability of retrospective computed tomographic (CT) studies for the purpose quantifying mandibular growth.
Vorperian, H.K., Wang, S., Schimek, E.M., Durtschi, R.D., Ziegert, A.J., Gentry, L.R. & Chung, M.K. (2011). Developmental sexual dimorphism of the oral and pharyngeal portions of the vocal tract: An imaging study. Journal of Speech, Language and Hearing Research, 54(4):995–1010. doi: 10.1044/1092-4388(2010/10-0097). PMCID: PMC3135757.
Summary/Significance: This study is the first to address a long standing question: What is the anatomic basis for differences in speech acoustics between developing boys and girls? Although there are documented sex differences in speech/vowel acoustics by age four to six years, anatomic differences in vocal tract length (that contribute towards substantial sex differences in speech acoustics) have only been documented between adolescents as well as adult men and women. This study unveiled the masking effect of sex differences in growth rate and documents the presence of developmental anatomic differences in specific regions of the vocal tract before puberty.
Seo., S., Chung, M.K., Whyms, B.J. & Vorperian, H.K. (2011). Mandible shape modeling using the second eigenfunction of the Laplace-Beltrami operator. Proceedings of SPIE 7962, 79620Z (2011). doi: 10.1117/12.877537.
Summary/Significance: The second Laplace-Beltrami eigenfunction was used to establish natural coordinates for elongated mandible shapes in CT. This approach was used to establish the centerline of segmented mandibles providing automated anatomic landmarks across subjects. These centerlines were then used to quantify the growth pattern of the mandible from birth to 20 years. Findings revealed significant condylar length increase and angle decrease during the course of development for both males and females. These findings confirm the documented downward and forward growth of the mandible.
Chung, M.K., Seo, S., Adluru, N. & Vorperian, H.K. (2011). Hot Spots Conjecture and Its Application to Modeling Tubular Structures. Medical Image Computing and Computer-Assisted Intervention: Machine learning in medical imaging, Lecture Notes in Computer Science. doi: 10.1007/978-3-642-24319-6_28.
Summary/Significance: The second eigenfunction of the Laplace-Beltrami operator was used to follow the pattern of the overall shape of the mandible/jaw that supports the tongue for speech production. This method extracted the centerline of the mandible as 3D curves which were subsequently used to model the growth of the mandible. Findings revealed significant sex differences in the growth of mandible size with male mandibles growing at a faster rate than female mandibles.
Milenkovic, P.H., Yaddanapudi, S., Vorperian, H.K. & Kent, R.D. (2010). Effects of a curved vocal tract with grid-generated tongue profile on low-order formants. Journal of the Acoustical Society of America, 127(2):1002–1013. doi: 10.1121/1.3277214. PMCID: PMC2830264.
Vorperian, H.K., Wang S., Chung M.K., Schimek, E.M., Durtschi R.B., Kent, R.D., Ziegert A.J. & Gentry L.R. (2009). Anatomic development of the oral and pharyngeal portions of the vocal tract: An imaging study. Journal of the Acoustical Society of America, 125(3):1666–1678. doi: 10.1121/1.3075589. PMCID: PMC2669667.
Vorperian, H.K. & Kent, R.D. (2007). Vowel acoustic space development in children: a synthesis of acoustic and anatomic data. Journal of Speech, Language, and Hearing Research, 50:1510-1545. doi: 10.1044/1092-4388(2007/104). PMCID: PMC2597712.
Vorperian, H.K., Kent, R.D., Lindstrom, M.J., Kalina, C.M., Gentry, L.R. & Yandell, B.S. (2005). Development of vocal tract length during early childhood: A Magentic Resonance Imaging Study. Journal of the Acoustical Society of America, 117(1):338–350. doi: 10.1121/1.1835958.
Callan, D.E., Kent, R.D., Gunther, F.H. & Vorperian, H.K. (2000). An auditory-feedback-based neural network model of speech production that is robust to developmental changes in the size and shape of the articulatory system. Journal of Speech, Language, and Hearing Research, 43(3):721–736. doi: 10.1044/jslhr.4303.721.
Vorperian, H.K., Kent, R.D., Gentry, L.R. & Yandell, B.S. (1999). MRI procedures to study the concurrent anatomic development of the vocal tract structures: Preliminary results. International Journal of Pediatric Otorhinolaryngology, 49(3):197–206. doi: 10.1016/S0165-5876(99)00208-6.