Posted on April 22nd, 2008
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Research in the Republic of Ireland
The Cleft Lip and Palate Association of Ireland is committed to supporting research into the causes and treatment of oral clefts. The Association also actively supports and encourages education and training opportunities which go towards improving the care and treatment given to persons born with a cleft lip and/or palate.
About: Speech research carried out at The Children’s Hospital, Temple Street, Dublin, between 1992 and 2000.
The results of this project have been presented at the 6th European Craniofacial Congress, Manchester 1999, and the American Cleft Palate and Craniofacial Conference, Atlanta 2000. It will also be presented at the International Cleft Palate and Craniofacial Meeting in Gotenborg, Sweden, June 2001. The project was funded by The Child Health Foundation, Temple Street, and has been accepted as a PhD thesis in Trinity College, Dublin.
The percptual and Instrumental Assessment of Nasality and nasal Airflow Errors Associated with Velopharyngeal Dysfunction.
Caitriona Sweeney, M.Sc., M.R.C.S.L.T.
[A dissertation submitted in fulfilment of the requirements for the degree of Doctor of Philosophy in the School of Clinical Speech and Language Studies, University of Dublin, Trinity College, and funded by The Child Health Foundation, Temple Street.]
Date: July 2000
This study aimed to develop a reliable and valid perceptual profile for the assessment of nasality and nasal airflow errors in speech. To date, clinicians rely on simple categorical or numerical scales of nasality and nasal airflow errors to assess speech. Such scales provide limited information on the type or degree of the presenting speech problems. This new scale aimed to describe the nature and the degree of these characteristics, thus improving reliability and validity. The second aim of the study was to assess the validity of the Perceptual Profile using instrumental assessment for investigations of nasality and nasal airflow errors and thus develop a protocol for assessment of nasality and nasal airflow errors in speech.
In order to develop the Perceptual Profile, working definitions of the terms used to describe nasality and nasal airflow errors were developed. The definitions formed the basis of the Perceptual Profile and qualitative descriptions of error categories were devised. The resulting scale was then tested rigorously for reliability, using percentage of agreement and kappa scores. Intra-rater reliability was assessed by rating the speech of twelve children presenting with nasality and/or nasal airflow errors twice from audio tape recordings. Results indicated good to excellent intra-rater reliability of the Perceptual Profile. Inter-rater reliability was assessed by comparing ratings of three Speech and Language Therapists (one specialist, one experienced and one inexperienced in the area). The speech samples of 20 children were analysed; percentage agreement and kappa scores were calculated for each pair of raters. Results indicated good inter-rater agreement for perceptual ratings of nasality and nasal airflow errors. However, kappa results were variable, ranging from good to poor. Agreements of ratings in the present study compared well with previous studies. The use of kappa analysis in the evaluation of reliability of nasality and nasal airflow assessment is new and comparison of the kappa analysis of the perceptual profile with other scales is not possible. The variable findings of reliability of the perceptual assessment demonstrates the need to supplement perceptual assessments with instrumental measurements.
Perceptual ratings of nasality were compared to instrumental measurements of nasality using the Nasometer, while perceptual ratings of nasal airflow errors were compared to instrumental measurements of flow and pressure using the PERCI SARS system. Normative data from instrumental measurements is required before instrumentation can be used to assess pathological speech. Normal pressure/flow measurements from 152 normal speaking children were obtained by Zajac (1998, personal communication). Previous studies have indicated the need to obtain local normative data for the Nasometer. In this study, seventy normal English-speaking Irish children were assessed on the Nasometer using a novel speech stimulus. The speech stimuli available to date have been found to be difficult for children (Watterson, Hinton & McFarlane, 1996) and the present study found that the American stimuli were culturally biased. The speech stimulus used for the present study allowed for nasometric analysis of sentences, which were categorised according to consonant type. The normative data obtained in the study will now provide baseline normal data for use of the Nasometer in Ireland.
Fifty children presenting with nasality and/or nasal airflow errors were assessed using the perceptual scale, the Nasometer and the pressure/flow system. Results were compared using correlational analysis, test sensitivity, specificity and overall efficiency ratings. Results indicated a strong relationship between perceptual ratings of nasality and nasalance scores on specific speech stimuli. There was a strong relationship between perceptual ratings of nasal emission and pressure/flow measurements, particularly nasal flow and velopharyngeal port area measurements. A weak relationship was found between pressure/flow measurements and perceptual ratings of the following nasal airflow errors: nasal turbulence, nasal fricatives and velopharyngeal fricatives.
Reliability and validity results identified sections of the Perceptual Profile that required revision. Overall results indicate that the Perceptual Profile has variable reliability, with acceptable agreement and, is a valid tool for the assessment of nasality and nasal airflow errors in the speech of children with velopharyngeal dysfunction. Results also indicate that the perceptual and instrumental assessment protocol is a valid and reliable assessment, which could be used in specialist centres for management of children with cleft palate and velopharyngeal dysfunction.
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