If you want to audit a single folder you can create Filter in Audit Trail

First Select the Even Types you want to audit, then add a filter below

SIngle:
Select Columns; Full Path
Select Criteria: Is Equal To
\Human Resources\John Doe\Medical
**This query will return only data for the medical folder**

Multiple Folders

Select Columns: Full Path
Select Criteria: is like
\Human Resoures\John Doe\
**This query will return all documents and folders under John Doe**