After bills are introduced in a Congress, they are assigned to an appropriate committee. If the bill is significant the committee will hold hearings to get views of interested parties as well as the opinions of experts in the focus area of the bill. Hearings are often less useful for determining intent because they are held to solicit information that may or may not be reflected in the language of the bill that comes out of committee. They are useful to reflect the political, economic, scientific, or social atmosphere that exists at the time the bill was introduced.
Committee websites, House and Senate, often include transcripts of committee hearings. Content may be transcripts submitted by witnesses to the Committee or the actual videorecorded hearing. Usually only available for hearings within the past 10 years but check the committee site as this varies.