The effects of hearing impairment on the person with the impairment and on their significant others are pervasive and affect the quality of life for all involved. The effect of hearing impairment on significant others is known as a third-party disability. This study aimed to develop and psychometrically test a scale to measure the third-party disability experienced by spouses of older people with hearing impairment. The Significant Other Scale for Hearing Disability (SOS-HEAR) was based on results of a previous qualitative study investigating the effect of hearing impairment on a spouse's everyday life. Psychometric testing with 100 spouses was conducted using item analysis, Cronbach's alpha, factor analysis, and test-retest reliability. Principal components analysis identified six key underlying factors. A combined set of 27 items was found to be reliable (alpha = 0.94), with weighted kappa for items ranging from fair to very good. The SOS-HEAR is a brief, easy to administer instrument that has evidence of reliability and validity. The SOS-HEAR could serve as a means of identifying spouses of older people with hearing impairment in need of intervention, directed towards either the couple or the spouse alone.