That would be easy Sunny. First the server would cost less than 10 dollars a month.
Second, HIPPA rules can be satisfied with good passwords.
Third each doctor could be given a sub_domain, Such as, Drhouse.sunny.net or kavorkian.sunny.net.
The doctors could upload their wav files and you could transcribe them.
This would be simple because you only need a main page with links to the doctors sub_domains.
When the doctors clicked on the main page link a *capcha box, their password box and user name would appear.
Lastly you need a page in the server to keep google bots, amazon bots ect out of the data files. This is simple and effective.
I hope you can understand this Sunny It sounds like a great idea.
* capcha keeps bots from spamming your server. Machines have problems reading irregular lettering.