The objective of this work was to build a 15-item short-form of the Speech Spatial and Qualities of Hearing Scale (SSQ) that maintains the three-factor structure of the full form, using a data-driven approach consistent with internationally recognized procedures for short-form building. This included the validation of the new short-form on an independent sample and an in-depth, comparative analysis of all existing, full and short SSQ forms.
Data from a previous study involving 98 normal-hearing (NH) individuals and 196 people with hearing impairments (HI), non hearing aid wearers, along with results from several other published SSQ studies, were used for developing the short-form. Data from a new and independent sample of 35 NH and 88 HI hearing aid wearers were used to validate the new short-form. Factor and hierarchical cluster analyses were used to check the factor structure and internal consistency of the new short-form. In addition, the new short-form was compared with all other SSQ forms, including the full SSQ, the German SSQ15, the SSQ12, and the SSQ5. Construct validity was further assessed by testing statistical relationships between scores and audiometric factors, including pure-tone threshold averages (PTAs) and left/right PTA asymmetry. Receiver-operating characteristic analyses were used to compare the ability of different SSQ forms to discriminate between NH and HI (HI non hearing aid wearers and HI hearing aid wearers) individuals.
Compared all other SSQ forms, including the full SSQ, the new short-form showed negligible cross-loading across the three main subscales and greater discriminatory power between NH and HI subjects (as indicated by a larger area under the receiver-operating characteristic curve), as well as between the main subscales (especially Speech and Qualities). Moreover, the new, 5-item Spatial subscale showed increased sensitivity to left/right PTA asymmetry. Very good internal consistency and homogeneity and high correlations with the SSQ were obtained for all short-forms.
While maintaining the three-factor structure of the full SSQ, and exceeding the latter in terms of construct validity and sensitivity to audiometric variables, the new 15-item SSQ affords a substantial reduction in the number of items and, thus, in test time. Based on overall scores, Speech subscores, or Spatial subscores, but not Qualities subscores, the 15-item SSQ appears to be more sensitive to differences in self-evaluated hearing abilities between NH and HI subjects than the full SSQ.