ORIGINAL ARTICLE Anthropometric and Demographic Correlates of Dual-Axis Swallowing Accelerometry Signal Characteristics: A Canonical Correlation Analysis Fady Hanna Æ Sonja M. Molfenter Æ Rebecca E. Cliffe Æ Tom Chau Æ Catriona M. Steele Published online: 3 June 2009 Ó Springer Science+Business Media, LLC 2009 Abstract Swallowing accelerometry has been proposed as a potential minimally invasive tool for collecting assessment information about swallowing. The first step toward using sounds and signals for dysphagia detection involves characterizing the healthy swallow. The purpose of this article is to explore systematic variations in swal- lowing accelerometry signals that can be attributed to demographic factors (such as participant gender and age) and anthropometric factors (such as weight and height). Data from 50 healthy participants (25 women and 25 men), ranging in age from 18 to 80 years and with approximately equal distribution across four age groups (18-35, 36-50, 51-65, 66 and older) were analyzed. Anthropometric and demographic variables of interest included participant age, gender, weight, height, body fat percent, neck circumfer- ence, and mandibular length. Dual-axis (superior-inferior and anterior-posterior) swallowing accelerometry signals were obtained for five saliva and five water swallows per participant. Several swallowing signal characteristics were derived for each swallowing task, including variance, amplitude distribution skewness, amplitude distribution kurtosis, signal memory, total signal energy, peak energy scale, and peak amplitude. Canonical correlation analysis was performed between the anthropometric/demographic variables and swallowing signal characteristics. No sig- nificant linear relationships were identified for saliva swallows or for superior-inferior axis accelerometry signals on water swallows. In the anterior-posterior axis, signal amplitude distribution kurtosis and signal memory were significantly correlated with age (r = 0.52, P = 0.047). These findings suggest that swallowing accelerometry signals may have task-specific associations with demo- graphic (but not anthropometric) factors. Given the limited sample size, our results should be interpreted with caution and replication studies with larger sample sizes are warranted. Keywords Swallowing Á Dysphagia Á Accelerometry Á Signal processing Á Cervical auscultation Á Deglutition Á Deglutition disorders Introduction The mechanical act of swallowing produces a source of vibration at the neck. The measurement of these vibrations is known as swallowing accelerometry. Accelerometry is closely related to cervical auscultation, the clinical tech- nique of listening to and interpreting acoustic information collected from the surface of the neck during swallowing. Both swallowing accelerometry and cervical ausculta- tion have been proposed as potentially useful and mini- mally invasive methods for detecting abnormalities in F. Hanna Á T. Chau Á C. M. Steele Institute of Biomaterials &Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada F. Hanna Á S. M. Molfenter Á R. E. Cliffe Á C. M. Steele (&) Toronto Rehabilitation Institute, 550 University Avenue, #12030, Toronto, ON, M5G 2A2, Canada e-mail: steele.catriona@torontorehab.on.ca R. E. Cliffe Á C. M. Steele Department of Speech-Language Pathology, University of Toronto, Toronto, ON M5G 1V7, Canada T. Chau Á C. M. Steele Bloorview Kids Rehab, Toronto, ON M4G 1R8, Canada T. Chau Á C. M. Steele Graduate Department of Rehabilitation Sciences, University of Toronto, Toronto, ON M5S 2Z9, Canada 123 Dysphagia (2010) 25:94–103 DOI 10.1007/s00455-009-9229-9