Historically, speech intelligibility has been the key measure of dysarthria severity, and both rating scales and orthographic transcription have been used as the primary forms of assessment. However, due to limitations in these measures, such as ceiling effects in transcriptions and subjective biases in rating scales, different forms of assessment are required to accurately assess speech severity in people with dysarthria. This study seeks to address these limitations by examining a new form of dysarthria assessment: listener reaction time. Listeners (one group of 16 younger adults, one of 16 older adults) performed three measures of speech intelligibility: a sentence transcription task, a rating scale task and reaction time task to veracity statements. These three measures were significantly correlated to one another, with reaction time accounting for 88% of the variance in transcription scores and 84% of the variance in the ratings of dysarthria provided by the younger listener group. Overall, the younger listeners produced significantly different reaction times when listening to speakers with dysarthria as compared to healthy control speakers. Reaction times between pairs of speakers (one with dysarthria, one control) were significantly different for all but the two speakers with the mildest dysarthria. In examining the older listener data, similar associations between assessment scores were found. However, the older listeners produced significantly longer reaction times than the younger group, and age and hearing loss were identified as significant factors for both reaction time and orthographic transcription.