Establishing valid and reliable measures for use with patients with disorders of consciousness (DOC) following profound brain injury is challenging due to a number of factors including the complex presentation of such patients and assessor variability. The auditory modality has been demonstrated to have greater sensitivity for detecting awareness in DOC patients. However, there are no measures developed to assess auditory responsiveness specifically. The objective of this study was to examine the psychometric properties of the principal subscale of a music therapy assessment tool (MATADOC) developed for use with adult DOC patients. The subscale assesses behavioural domains essential for diagnosis of awareness. Twenty-one adult patients were recruited from a specialist rehabilitation unit. In a prospective study with repeated measures, internal consistency, inter-rater and test-retest reliability and dimensionality were examined. The five-item scale showed satisfactory internal reliability (α = .76) and a strong first principal component. Corrected item-total correlations were all > .45. Inter-rater intra-class correlations (ICCs) ranged from 0.65-1.00 and intra-rater ICCs from 0.77-0.90. Rasch analysis confirmed these impressions of a reliable, unidimensional and homogenous scale. Diagnostic outcomes had 100% agreement with a validated external reference standard. The results indicate that the MATADOC principal subscale provides a new behavioural measure that can contribute to interdisciplinary assessment of awareness with DOC patients.