Physiological assessment of speech and voice production of adults with hearing loss.

The purpose of this investigation was to study the impact of hearing loss on phonatory, velopharyngeal, and articulatory functioning using a comprehensive physiological approach. Electroglottograph (EGG), nasal/oral air flow, and intraoral air pressure signals were recorded simultaneously from adults with impaired and normal hearing as they produced syllables and words of varying physiological difficulty. The individuals with moderate-to-profound hearing loss had good to excellent oral communication skills. Intraoral pressure, nasal air flow, durations of lip, velum, and vocal fold articulations, estimated subglottal pressure, mean phonatory air flow, fundamental frequency, and EGG abduction quotient were compared between the two subject groups. Data from the subjects with hearing loss also were compared across aided and unaided conditions to investigate the influence of auditory feedback on speech motor control. The speakers with hearing loss had significantly higher intraoral pressures, subglottal pressures, laryngeal resistances, and fundamental frequencies than those with normal hearing. There was notable between-subject variability. All of the individuals with profound hearing loss had at least one speech/voice physiology measure that fell outside of the normal range, and most of the subjects demonstrated unique clusters of abnormal behaviors. Abnormal behaviors were more evident in the phonatory than articulatory or velopharyngeal systems and were generally consistent with vocal fold hyperconstriction. There was evidence from individual data that vocal fold posturing influenced articulatory timing. The results did not support the idea that the speech production skills of adults with moderate-to-profound hearing loss who are good oral communicators deteriorate when there are increased motoric demands on the velopharyngeal and phonatory mechanism. Although no significant differences were found between the aided and unaided conditions, 7 of 10 subjects showed the same direction of change for subglottal pressure, intraoral pressure, nasal air flow, and the duration of lip and vocal fold articulations. We conclude that physiological assessments provide important information about the speech/voice production abilities of individuals with moderate-to-profound hearing loss and are a valuable addition to standard assessment batteries.