In this position paper we argue for the need of using standardized questionnaires for assessing usability in audio-visual representations. By using standardized measures of usability, comparability and validity of research studies in this field will be improved. However, it is not clear which questionnaire that is most suitable for assessing usability in audio-visual representations, neither when assessing the modalities individually or the combination. We present a variety of different questionnaires available, and argue for the need of combining different measures as well as developing new.