Effects of consonantal context on vowel lipreading

The effects of consonantal context on vowel lipreading were assessed for 30 adults with mild-to-moderate sensorineural hearing loss who lipread videotape recordings of two female talkers. The stimuli were the vowels /i,I,alpha,U,u/ in symmetric CVC form with the consonants /p,b,f,v,t,d,f,g/ and in the asymmetric consonantal contexts /h/-V-/g/, /w/-V-/g/, /r/-V-/g/. Analyses of the confusion matrices from each talker indicated that vowel intelligibility was significantly poorer in most contexts involving highly visible consonants, although the utterances of one talker were highly intelligible in the bilabial context. Among the visible contexts, the fricative and labiodental contexts in particular produced the lowest vowel intelligibility regardless of talker. Lax vowels were consistently more difficult to perceive than tense vowels. Implications for talker selection and refinement of the concept of viseme were drawn.