Dear Rich: I have a question. I am a science journalist and I've recorded interviews with many famous scientists. I've used this material in books and articles and would now like to use these on a website for free, open-access listening. Someone has suggested that I obtain permissions from all my subjects or their estates. I believe that no permissions are required because the subjects implicitly granted me permission to use the interview material as I saw fit when they sat down with me and my tape recorder and pad. I'm so glad you asked. You are navigating through one of the grayer areas of copyright law so in answering, I'll have to use a lot of equivocating language, such as 'likely,' 'may,' and 'probably.' If you don't have time to read all of that stuff, the bottom line is that you are probably okay to do what you plan to do. The courts and legal scholars are not a beacon of clarity when it comes to divvying up the rights for interviews.
From the limited case law available, it's likely that a court will consider an interview to consist of two separate works: one work created by the interviewer's questions, and the other created by the subject's responses. These works may be protected under traditional copyright principles (or they may be protected under what's referred to as common law copyright). Under that 'two-separate works' approach, you'd need permission to reproduce the subject's answers. That permission may be implied by the subject's consent to the interview. In fact, one court -- dealing with an interview with Ernest Hemingway -- hinted that Hemingway's failure to limit usage at the time of the interview implied unlimited use.
Some legal scholars argue that a better approach is that the interviewer and subject jointly create one work. Under that analysis, the interviewer and the subject are joint authors. In that case, either author can use the interview for any purpose provided that the party using the interview accounts to the other for any profits. If this approach were applied to your case, your use should be fine since you are distributing the interviews for free and (assuming you are not making money off the website) no accounting would be necessary. You can read more on these two approaches at the Publaw.com site. Also, as you are probably aware, if you proceed without permission, you would have a strong fair use argument for distributing these interviews based on their historic and scientific value.
The whole thing becomes more complicated if you are making money from the sale or licensing of the recordings -- a situation that may trigger a right of publicity claim or (if you and the subject are considered joint authors) an accounting of moneys earned to the interview subject. Finally, there is some question as to whether federal copyright protection extends to a recorded interview, since simultaneous recording of the performance of a work of authorship (that is, not being broadcast) is not considered to be fixed. That means that the interview is not protectable under copyright law (hence the need to use common law copyright, as described above). There's no guarantee that this will all play out as described. A lawyer would advise you that the only 100% safe course is to obtain permissions. But I think your chances of avoiding hassles are good and I personally look forward to listening to the interviews. There is always so much to learn about our scientific heroes.