A Comparison of Equal-appearing Interval Scaling and Direct Magnitude Estimation in the Perceptual Judgment of Hypernasality

Ha, Seunghee

ORIGINAL ARTICLE

Commun Sci Disord. 2009;14(4): 563-573.

Seunghee Ha^`

하승희(Seunghee Ha)

ABSTRACT

Background & Objectives
It is important to use a valid and appropriate scaling system for the perceptual evaluation of speech disorders, including hypernasality. Although equal-appearing interval scaling (EAI) is the most popular scaling system for the evaluation of hypernasality in clinical settings and research, there are concerns about the validity of this method for hypernasality. The purpose of this study was to compare EAI and Direct Magnitude Estimation (DME), which is another scaling system for the perceptual judgment of hypernasality, and to determine which scaling system is more valid.
Methods
Speech samples were obtained from 28 children with cleft palate, and 10 listeners performed the perceptual evaluation of hypernasality using EAI and DME. The relationship between the results from the EAI and DME were investigated based on visual inspection and analysis of models.
Results
Visual inspection and analysis of models demonstrated a curvilinear relationship between the two measures.
Discussion & Conclusion
The results suggest that listeners have difficulty partitioning hypernasality into equal-appearing intervals because hypernasality is additive, quantitative, and prothetic in nature. These findings verify that the DME is a more valid method for the evaluation of hypernasality than the EAI