Applications whose functionality poses a risk to a patient’s safety if the mobile app were to not function as intended are considered mobile medical applications. Therefore app to retain the auditory cues is considered the mobile medical application. Furthermore, FDA states that “Mobile apps that use tools within the mobile platform (e.g., speaker) to produce controlled levels of test tones and signals intended for use in conducting diagnostic hearing evaluations and assisting in the diagnosis of possible otologic disorders (i.e., an audiometer). Possible product code: EWO (21 CFR 874.1050).”
One of the example of the Mobile medical application is MedDream DICOM which received a 510k approval recently. Its main function is to search, view and analyze medical devices.

Source: http://www.fda.gov/MedicalDevices/DigitalHealth/MobileMedicalApplications/ucm368743.htm