|Mannerheim is on Hitler's left.|
History heretofore has had only a single recording of how the man actually spoke in private.
This single recording of Hitler kicking back, speaking "off the record" among his cronies exists thanks to the Finns, in whom Hitler was hoping to find an ally to open a new front in his losing war on Russia. But for the Finns, it was a matter of, been there done that. Their war with Russia was over.
Here is the Finnish website that offers the recording, which is included on this web page, below, as an embed.
Carl Gustaf Emil Mannerheim was the Commander-in-Chief of Finland's Defence Forces in 1942. That year, when Mannerheim turned 75 he received a surprise visit from Adolf Hitler. (Hitler lived "irregularly," as he said, always changing his schedule at the last minute. It was his primary way of avoiding assassination, and as history records, it worked several times.).
Recordings of Hitler's private conversations were strictly forbidden. But sound engineer Thor Damen threw a festive trolley overhead and hid a microphone in it, recording Hitler.
This original 11-minute episode is reportedly the only recording of Hitler not speaking for public consumption, though he was of course conversing with a potential ally who could help him fight Russia, so obviously he had some agenda, but we get to hear him speaking in a normal voice.
Here's the recording:
Actor Bruno Ganz listened to the tape in preparation for playing Hitler in the film Der Untergang -- Downfall, in English (2004).
The discussion touched on such topics as Mannerheim noting that the Finns in the Winter War (their short war with the Soviets in which they fought extremely well though lost in the end) had no idea how well-armed the Soviet Union was. The remainder of the recording is essentially a monologue of Hitler.
He discussed how Germany's plan had been to invade the West in 1939, but the project had to be postponed due to weather until spring 1940. Turning east as he eventually did was postponed due to difficulties the Axis encountered in North Africa and the Balkans.
Here is one website's wider historical take on the subject:
Adolf Hitler decided to visit Finland on 4 June 1942, ostensibly to congratulate Mannerheim on his 75th birthday. But Mannerheim did not want to meet him in his headquarters in Mikkeli or in Helsinki, as it would have seemed like an official state visit. The meeting took place near Imatra, in south-eastern Finland, and was arranged in secrecy.
From Immola Airfield, Hitler, accompanied by President Ryti, was driven to the place where Mannerheim was waiting at a railway siding. After a speech from Hitler, and following a birthday meal and negotiations between him and Mannerheim, Hitler returned to Germany. President Ryti and other high-ranking Finns and Germans were also present. Hitler spent about five hours in Finland. Hitler reportedly intended to ask the Finns to step up military operations against the Soviets, but he apparently made no specific demands.
During the visit, an engineer of the Finnish broadcasting company YLE, Thor Damen, succeeded in recording the first 11 minutes of Hitler's and Mannerheim's private conversation. This had to be done secretly, as Hitler never allowed others to record him off-guard. Damen was given the assignment to record the official birthday speeches and Mannerheim's responses and following those orders added microphones to certain railway cars. Unfortunately, Mannerheim and his guests chose to go to a car that didn't have a microphone in it. Damen acted quickly, pushing a microphone through one of the car windows to a netshelf just above were Hitler and Mannerheim were sitting. After 11 minutes of Hitler's and Mannerheim's private conversation, Hitler's SS bodyguards spotted the cords coming out of the window and realized that the Finnish engineer was recording the conversation. They gestured to him to stop recording immediately, and he complied. The SS bodyguards demanded that the tape be immediately destroyed, but YLE was allowed to keep the reel, after promising to keep it in a sealed container. It was given to the head of the state censors' office Kustaa Vilkuna and in 1957 returned to YLE. It was made available to the public a few years later. It is the only known recording of Hitler speaking in an unofficial tone.
There is an unsubstantiated story that during his meeting with Hitler, Mannerheim lit a cigar. Mannerheim supposed that Hitler would ask Finland for help against the Soviet Union, which Mannerheim was unwilling to give. When Mannerheim lit up, all in attendance gasped, for Hitler's aversion to smoking was well known. Yet Hitler continued the conversation calmly, with no comment. In this way, Mannerheim could judge if Hitler was speaking from a position of strength or weakness. He was able to refuse Hitler, knowing that Hitler was in a weak position, and could not dictate to him.