Study designs of evaluations included in the review
Studies with at least one participant were eligible. Studies that provided only general descriptions of the strategies used were excluded. There were no other inclusion criteria for the study design.
Specific interventions included in the review
Studies of speech supplementation techniques were eligible for inclusion. The review assessed the effects of alphabet cues, semantic cues, gestures, combinations of strategies, and syntactic cues. In most of the included studies, speakers read prepared sets of words and/or sentences. The studies used various electronic modes to present stimuli from a variety of sources (details were reported). All studies were conducted in experimental situations.
Participants included in the review
Studies of patients with dysarthria were eligible for inclusion. Studies of patients with unintelligible speech due to hearing impairment or other disorders were excluded. The included studies were of patients with a variety of medical diagnoses, the most common being cerebral palsy, cerebrovascular accident and traumatic brain injury. Other diagnoses were amyotrophic lateral sclerosis and Parkinson's disease. The participants had different types of dysarthria, including flaccid, mixed, spastic, athetoid and hypokinetic (reported in 12 studies). Most of the participants were adults but the age range was great (9 to 87 years). The reviewers considered most participants to have severe or profound speech unintelligibility.
Outcomes assessed in the review
Inclusion criteria for the outcomes were not specified. The included studies most commonly measured outcomes by assessing intelligibility using the accuracy of the listeners' transcription of the speakers' message. Studies also assessed speaking rate, speech duration and comprehension. Listeners were most commonly undergraduates or graduate level students; none of the listeners were members of the general public.
How were decisions on the relevance of primary studies made?
Two authors reviewed the identified studies.