Speaker Failure with Facetime

I recently purchased Facetime from the App store for my OS X. Within 30 minutes - 1 hr of the app running, the auditory function diminishes and the person on the receiving end is no longer able to hear me, however, I am able to hear them clearly. This is a continuous problem, occuring every time I run the App. Input and Output volume are as high as they can go. Does anyone have any ideas as to what may be occuring and how I can fix this problem?

S.S