Underlying dimensions and individual differences in auditory, visual, and auditory-visual vowel perception by hearing-impaired children

Vowel perception studies were conducted on a group of four adolescent children with congenital profound sensorineural hearing impairments in the three conditions of audition alone, vision alone, and audition plus vision. Data were analyzed using the ALSCAL multidimensional scaling procedure to identify the underlying dimensions and individual differences in dimension emphasis. The three dimensions obtained from the analysis of data for the audition alone condition were interpreted as the parameters of first and second formant frequencies, and vowel length. The one dimension for the vision alone condition was interpreted as the parameter of the width of the internal lip opening. The three dimensions for the audition plus vision condition were interpreted as the parameters of first formant frequency, vowel length, and the width of the internal lip opening. Subject variations in parameter preferences were observed for the audition alone and audition plus vision conditions but not for the vision alone condition.