Control of vocal loudness in young and old adults

This study examined the effect of aging on respiratory and laryngeal mechan isms involved in vocal loudness control. Simultaneous measures of subglotta l pressure and electromyographic (EMG) activity from the thyroarytenoid (TA ), lateral cricoarytenoid (LCA), and cricorhyroid (CT) muscles were investi gated in young and old individuals while they attempted to phonate at three loudness levels, "soft," "comfortable," and "loud." Voice sound pressure l evel (SPL) and fundamental frequency (F-0) measures were also obtained. Acr oss loudness conditions, subglottal pressure levels were similar for both a ge groups. Laryngeal EMG measures tended to be lower and more variable for old compared with young individuals. These differences were most apparent f or the TA muscle. Finally, across the three loudness conditions, the old in dividuals generated SPLs that were lower overall than those produced by the young individuals but modulated loudness levels in a manner similar to tha t of the young subjects. These findings suggest that the laryngeal mechanis m may be more affected than the respiratory system in these old individuals and that these changes may affect vocal loudness levels.