Dissociation between singing and speaking in expressive aphasia: The role of song familiarity

There are several reports on the ability aphasic patients have to sing familiar songs, despite having severe speech impairments. Based on these observations it was also suggested that singing might improve speech production. However, recent experimental studies with aphasic patients found no evidence to illustrate that singing improves word production under controlled experimental conditions. This study investigated the role of singing during repetition of word phrases in a patient severely affected with non-fluent aphasia (GS) who had an almost complete lesion of the left hemisphere. GS showed a pronounced increase in the number of correctly reproduced words during singing as compared to speaking excerpts of familiar lyrics. This dissociation between singing and speaking was not seen for novel song lyrics, regardless of whether these were coupled with an unfamiliar, a familiar, or a spontaneously generated melody during the singing conditions. These findings propose that singing might help word phrase production in at least some cases of severe expressive aphasia. However, the association of melody and text in long-term memory seems to be responsible for this effect.