Let’s say you have a theater with a gigantic curtain over the stage and behind the curtain is either some kind of real life event happening or some kind of speaker setup that’s designed to replicate the audio of that event. It could be a single person singing, an entire orchestra, a jackhammer going off, a drone flying around, whatever.
Are there certain scenarios where a layperson sitting in the audience would easily be able to tell the difference between the real thing and an audio recording? Or are speakers good enough that any conceivable event can be replicated accurately by the right set of speakers to the limits of human perceptibility?
What about headphones? Imagine if you blind someone and numb their ears so they can’t feel the pressure of headphones on their head. Can headphones represent exactly any possible soundscape or are there scenarios they would struggle with?
Of course, real-life events on stage often have their sound piped through speakers/amps, so I assume you’re comparing natural, unamplified sound to what comes out of speakers.
Headphones can’t possibly fool a listener to make them think they’re not wearing a headset. When a person is listening to a soundspace they can turn their head and will do so slightly in an unconscious way to pick up audio cues from around the room. I suppose you could emulate this with a headset by closely tracking a person’s head position and changing the audio to match, but I’m pretty doubtful that that approach would work well or be convincing.
I remember Lou Reed’s live record “Take No Prisoners” which starts with him striking a match close to the microphone, lightning a cigarette and saying: “Hello? Sorry we were late, but we were just tuning”. Then the concert starts with the usual claps, intro, Lou arrogant snark and so on. The first time you heard this (released in 1978) you just had to jump, no matter how cheap your boxes were: he sounded like he was in the room, jumping from the left to the right speaker, when you did not expect him at all.
I can remember when I was a teenager, there used to be this commercial that would play on the radio, and it would start off with the police siren going off. And every time I would have to look in my rear view mirror because I thought there was a cop behind me.
The reason that we can tell where a sound is coming from is because the shape of our ear causes different frequencies to be modulated depending on where the sound is coming from. Everything between your eardrum and the sound causes certain frequencies to be filtered. All those folds and waves in the skin of our ears causes the sound to change as it travels to our eardrum. Your brain learns to associate certain frequency drop offs with sound position and is able to pinpoint where the sound is coming from. Speakers and electronics can replicate this process. When you’re wearing headphones, a computer can make these same sound modifications to fool your brain into thinking the sound is coming from above, below, front, back, etc. even though the speaker and your eardrum are in fixed positions.
However, the folds and waves of each person’s ear are unique, similar to fingerprints. The spacial frequency patterns that your brain knows from your own ears may not exactly match the computer’s frequency patterns. If you were in theater setting, you might be able to sense that the sound versus position was a little off. But if the computer was able to learn the frequency pattern for your specific ears, then it would likely be able to do a virtually perfect job of faking sound position.
You can set up a speaker system for wavefield synthesis/ambisonic type surround sound—I guess they do in some theatres— has anyone been, who can report how good it sounds?