Performance of normal speakers on an index of velopharyngeal function

The Zemlin Index of Palatopharyngeal Opening (ZIPPO) is a non-invasive method for evaluation of velopharyngeal function. The present study was undertaken to assess the performance of normal speakers during ZIPPO testing. One hundred measurements of vocal damping times were made for each of 15 young, adult women as they produced the vowel/i/into ZIPPO. The vocal damping times of some speakers were characterized by extensive variability, suggesting that additional work is needed to specify the sampling requird to derive adequate information about the ZIPPO. Although the clinical application of the ZIPPO was not determined in this project, the sound theoretical framework and ease of ZIPPO administration provide sufficient grounds to prompt needed research into its clinical application.