Visual Cues Contribute Differentially to Audiovisual Perception of Consonants and Vowels in Improving Recognition and Reducing Cognitive Demands in Listeners With Hearing Impairment Using Hearing Aids

Shahram Moradi, Björn Lidestam, Henrik Danielsson, Elaine Hoi Ning Ng, Jerker Rönnberg

We sought to examine the contribution of visual cues in audiovisual identification of consonants and vowels-in terms of isolation points (the shortest time required for correct identification of a speech stimulus), accuracy, and cognitive demands-in listeners with hearing impairment using hearing aids. The study comprised 199 participants with hearing impairment (mean age = 61.1 years) with bilateral, symmetrical, mild-to-severe sensorineural hearing loss. Gated Swedish consonants and vowels were presented aurally and audiovisually to participants. Linear amplification was adjusted for each participant to assure audibility. The reading span test was used to measure participants' working memory capacity. Audiovisual presentation resulted in shortened isolation points and improved accuracy for consonants and vowels relative to auditory-only presentation. This benefit was more evident for consonants than vowels. In addition, correlations and subsequent analyses revealed that listeners with higher scores on the reading span test identified both consonants and vowels earlier in auditory-only presentation, but only vowels (not consonants) in audiovisual presentation. Consonants and vowels differed in terms of the benefits afforded from their associative visual cues, as indicated by the degree of audiovisual benefit and reduction in cognitive demands linked to the identification of consonants and vowels presented audiovisually.