Hello,
I think during capstone project the application your team developed is considered to be mobile medical app because it allows people to retain their auditory stimuli. Furthermore, mobile medical application is something that can help people manage their own health and wellness, promote healthy living, and gain access to useful information when and where they need it and your device will improve people’s lifestyle and health. FDA regulates certain mobile medical apps that are moderate-risk (class II) and high risk (class III) but I think your app should considered class I due to low risk and regulatory requirement is general control.
While searching through internet, I found the mobile medical app LactMed developed and maintained by National Institutes of Health which provides nursing mothers with information on drugs and other chemicals about the effects on breast milk and nursing infants. It also detect how these drugs impact an infant’s well-being and inform safe maternal and infant drug levels as well.
Link is provided to see which mobile medical apps that may meet the definition of medical device and for which FDA intends to exercise enforcement discretion.
http://www.fda.gov/MedicalDevices/DigitalHealth/MobileMedicalApplications/ucm368744.htm
FDA also updated App lists for mobile medical apps

FDA updates app lists for Mobile Medical Apps