The app is available for free on both Android and iPhones on Google Play and App Store respectively. The landing page address for links to both can be found here.
Check it out! Otherwise, you can go straight to the store below:
Dr. Christopher Chang is a private practice otolaryngology, head & neck surgeon specializing in the treatment of problems related to the ear, nose, and throat. Located in Warrenton, VA about 45 minutes west of Washington DC, he also provides inhalant allergy testing/treatment, hearing tests, and dispenses hearing aids. Google+ Christopher Chang, MD Bio