The Conversation works as the best kind of psychological thrillers do – on the heart and the head and the guts all at the same time, pulling you deeper and deeper in. It's imaginatively laid out but with surprisingly little artifice or what we would call "cinematic pizzazz". It's very simply made, though you can't help wondering how easy it would be to get it made these days because of the extraordinarily leisurely way it unfolds. I think we've lost our appetite now, unfortunately, for movies that try to get inside somebody's head.

I first saw it just before I left the UK for America, to work in radio drama. That's one of the reasons I found it so absorbing – the film's subject is a world perceived through the ear, not the eye. It is very carefully constructed in terms of the dynamics of sound, the alternations of noise and silence. These rhythms have stuck in my head for 30 years.

The core of the film is an absolutely brilliant performance by Gene Hackman. You don't really see into his eyes at all so the performance is conveyed through body language and vocal tone. I have tried to work with Hackman. It would be invidious of me to say what on because in the end I couldn't get him so somebody else played the part. He is a difficult guy to pin down these days; he doesn't really go to work that often and I think it has to be something he is overwhelmingly motivated to do. He is quite hard to reach but he is an astounding actor.

The Debt, directed by John Madden, is out on DVD and Blu-ray