Little is known about the effects of listener characteristics or listening conditions on intelligibility scores. This study compared intelligibility scores of dysarthric speech achieved under a standard listening condition with those obtained in non-standard conditions and investigated the effect of listener age, gender and familiarity with speaker accent on intelligibility scores. No differences were observed in the mean intelligibility scores across standard and non-standard listening conditions. However, mean range of scores in the standard condition was lower than in the non-standard condition (t = 3.07, df 90, p less than 0.003; 95% CI 2.04-9.76). No main effects of listener age, gender or familiarity of accent were observed. When composite effects were examined increased age in male listeners was associated with reduced intelligibility scores. Results from the current study suggest that when conducting intelligibility research listening conditions should be standardised and that adult listeners of either gender and any age may be used to test intelligibility outcomes providing hearing acuity is taken into consideration. (Contains 2 tables.)