Aisin Gioro Puyi testified against the Japanese Imperialism in the Tokyo War Crimes trials. The link contains Puyi's recorded voice back in 1946. Rare chance to hear the last emperor's actual recorded voice.
In Puyi's diaries, he said the 8 days where he served as a witness was very difficult. Even though he wasn't put on trail, the lawyers came at him with some very difficult to answer questions, trying to tie his actions and decisions with those of the war criminals. He would often resort to saying "I don't know" or "I don't recall" to avoid answering those questions. Finally, he came up with a plan, on the 8th day he said he would reveal his interactions with the Japanese emperor on the next day, and he wasn't called to the witness stand again for the reminder of the trail.