Legislative - attached to pending legislation
Investigative - investigate particular topic
Oversight - examine impact and efficiency of established laws
Types of Committee Hearings CRS Report, 2015
FDsys - Limited amount available from 105th Congress (1997-98) to present
Catalog of U.S. Government Publications - Pdf copies of hearings from mid 1990's to present. Select Browse tab and choose Internet Publications under Catalogs to Search and search by title or keyword.
Try googling the title of the hearing.