A research article from the Vocal Tract Development Laboratory at the Waisman Center (Principal Investigator, Houri K. Vorperian, Ph.D.) is the recipient of the 2010 Editor’s Award for the Speech section of the Journal of Speech, Language, and Hearing Research. The American Speech-Language Hearing Association awards this honor annually to the one article that meets the highest quality standards in research design, presentation, and impact.
“Developmental Sexual Dimorphism of the Oral and Pharyngeal Portions of the Vocal Tract: An Imaging Study,” addresses a question that has puzzled Speech Scientists. Namely, what is the anatomic basis for differences in speech acoustics between developing boys and girls? There are documented sex differences in speech/vowel acoustics by age four to six years. However anatomic differences in vocal tract length (the resonating system extending from the larynx to the lips), that contribute towards substantial sex differences in speech acoustics, have only been documented between adolescents as well as adult men and women. This is the first article that reports on developmental anatomic differences of the vocal tract before puberty.
Researchers in Dr. Vorperian’s laboratory used 605 medical imaging studies (MRI & CT) from males and females between the ages birth to 19 years, and measured nine areas in the oral (mouth) and pharyngeal (throat) regions. To make sure possible sex differences are not masked by differences in growth rate (a finding recently reported by this lab, Vorperian et al. 2009), this study used a localized comparison window of 5 years. Anatomic sex differences were evident in the oral region between the ages three and seven years. This was followed by significant sex specific differences of segments in the pharyngeal region at about eight years of age. This study confirmed the sensitivity of such an analysis approach to show sex differences before, during and after puberty, and also revealed that such sex differences change during the course of development. These findings are the first to show an anatomic basis for the known speech acoustic differences before puberty. Computer modeling studies are now underway to experimentally validate these anatomic–acoustic relationships.
The Vocal Tract Development Laboratory was established by Dr. Houri K. Vorperian at the Waisman Center in 1995 with funding support since 2000 from the National Institute of Deafness and Other Communication Disorders; also, with partial support from the Friends of the Waisman Center. Using multidisciplinary research, the mission of the Vocal Tract Development Laboratory is to quantify the three-dimensional anatomic development of the speech apparatus – which includes structures and cavities in the mouth and throat regions – throughout the lifespan in individuals with typical and atypical development, within the context of establishing anatomic-acoustic correlates. This cutting edge research will give us a better understanding of typical development of speech that is a foundation for the lab’s ongoing studies of Down syndrome and cerebral palsy.