The Auckland Auditory Imagery Scale: Exploring relationships between the mind’s ear, inner voice and clarity of sounds heard in dreams

We report the development and psychometric properties of The Auckland Scale of Auditory Imagery (AAIS), a new instrument providing concurrent assessment of distinct aspects of auditory imagery. Preliminary analyses of 32 candidate items suggested three factors corresponding to clarity of: imaginary sounds ‘heard’ in the mind’s ear; inner voice imagery; and sounds ‘heard’ in night dreams. The same three factors emerged in a follow-up study (N=293) applying factor analysis to 15 selected items. Responses within the three subscales were highly consistent, with values of Cronbach’s alpha exceeding .9 and minimal cross-loadings between factors. Strong factor loadings for individual items suggested potential for assessing AAIS auditory imagery factors with a very brief scale. While mind’s ear and inner voice imagery were moderately correlated (r = .63), some individuals reporting complete absence of mind’s ear imagery reported typical inner voice imagery. The converse dissociation - typical mind’s ear imagery co-occurring with absent inner voice imagery - was very rare. Rated clarity of voices, music and other sounds ‘heard’ during night dreams was lower for participants reporting absence of waking mind’s ear or inner voice imagery compared to participants with typical waking auditory imagery.  Nevertheless, 20%-30% of individuals reporting absence of waking auditory imagery reported hearing sounds in their night dreams with a degree of clarity comparable to that experienced by participants with typical imagery.  Theoretical implications of these findings together with the potential value of the AAIS for future investigations of auditory imagery are discussed.