If when a recording is made the sound you capture sounds different when it is live than when it is played back,and you can tell live from..?

I'm not really sure what your question is or what point you are trying to make.

If you are asking if a recording of something sounds the same as "the real thing" then it's impossible to give a simple answer. It depends on what is recorded, how it has been recorded, how it is being re-produced and context.

I have an electronic keyboard that I play through a pair of active monitor speakers. I do not believe that anyone could perceive any difference at all in sound between the keyboard being played "live" and a recording of it being played back over the same speakers (assuming no processing of any kind had taken place with the recording).

On the other hand, I believe that a person could tell the difference between an actual performance of a full orchestra and choir (i.e. they were sitting in the audience during the performance) and a recording of the same performance.

In the example you give, of recordings of troop movements, I think that expectations would play a major part: outside, whilst at war, soldiers would not expect to hear recordings of any kind. They would not be surprised though to hear troop movements. If, on the other hand, they had heard an orchestra playing, they would have been surprised but would probably have assumed the sound to be a recording as an actual orchestra playing on the battle field would be SO unlikely. If I was driving along the road and I heard the sound of a siren, I would automatically assume that there was an actual emergency vehicle nearby, not that a passenger was playing a recording. A recording of such a sound would not have to be particularly high quality to "fool me".

Usually, recorded sound, especially music, sounds quite different to the "live" equivalent. I can usually tell from outside whether the sound coming from a nearby building is "live" music or a recording (a record or CD etc.).

I'm sure that it would be possible to produce recordings that were impossible to tell from "the real thing" but they would need to be tecorded with this objective and would need to be listened to in a specific environment. I have never heard such a recording.

Sorry, I can't tell from your question whether you believe the "sonic deception" would fool the Nazis or not. Apparently it did, in spite of what your audiophile friends believe.

Consider this. First, Bell Labs apparently put a lot of thought into how the recordings were made so as to achieve the most believable sound. Then, consider the environment. Lots of ambient noise being made by the Nazi troops, and the fog of battle. Also consider that combat soldiers in the 1940's weren't audiophiles. Heck, some of them had probably never heard a phonograph. They weren't even remotely expecting the possibility that somebody was trying to fool them with a giant sound truck and spoofed recordings. Standing in a war zone and hearing something that sounds like approaching tanks, would the average soldier stop to think "is it real or is it Memorex?"

We can argue about whether you could tell the difference under ideal conditions. I think this was one of those situations where it didn't have to sound totally real...just real enough.

The answer is easy.

At a certain distance and environment, a recorded sound and the real sound can be indistinguishable. Especially considering that the sound used was supposed to travel miles around, at that distance, you would not be able to know.

Think about how it happens in reverse. Take a binaural record and listen to it with headphones. You know it's a recording yet to your ears and brain it sounds like the real thing. Sound deception is just like that but in reverse. Because of the distance and environment, even the original signal can be perceived such that it sounds like the real thing to the listener.

Basically, you have to think about context, context, context.