Disclosed herein, among other things, are methods and apparatus for identifying one or more defective hearing aids. The present system provides a dichotic sound to the wearer that can be used to sense whether the aids are properly operating. Different types of dichotic sounds can be presented within the scope of the present subject matter. In various applications a Huggins pitch, a binaural edge pitch, a binaural coherence edge pitch, a Fourcin pitch or a dichotic repetition pitch is used for the dichotic sound. The pitch may be a pure-tone or complex-tone pitch. Various pure-tone frequencies and complex-tone fundamental frequencies may be used and may be customized for a particular application. In various applications, a dichotic sound is formed using left and right sounds each of which includes a noise and a desired signal component. The present system can be realized in a variety of implementations.