Psychologists call this visual capture because the image seems to have captured the sound and taken it from where it should be to where the our visually-based interpretation needs it to be. And the rock concert is even the best example – the sound is coming from the speakers, not the performers but after all, it is the actions of the rock band that cause the speakers to make the sound in the first place – and so, like two wrongs making a right, our perception correctly shifts the sound back to its original source – the guitarist, the bassist, the drummer. Now this is an illusion, our brains are wrong in allowing this to happen – and yet who can deny the adaptability of the illusion? The puppet act is much more enjoyable if we imagine the puppet actually has its own voice, and the movie is much more understandable if we perceive the voices and sound effects emanating from the screen. I heartily recommend enjoying the perceptual experience of Rush in concert. But if we aren’t concentrating on sound localization per se, the sound will seem to be coming from the movie screen, or the performers in the middle of the stage. Speakers – often large, often clearly visible – are located in the walls of the cinema or left and right of the performers on stage. We’re the ones “throwing voices” around – in this case from the ceiling to the front of the room! If the classroom situation isn’t relatable, consider a movie theater or a rock concert. We can, to be sure, but only after willfully shifting our attention from visual analysis to auditory analysis. Given the impressive auditory localization abilities described in my last post, shouldn’t we quite naturally perceive the sound as emanating from above us, and not from the ghostly image in front of us? Where is the voice coming from? In most classrooms, from speakers placed in the ceiling above the students’ heads. There is no talking person there, only the image of a talking person, and voices don’t emanate from projection screens. The visual image of the scientist is being projected onto a screen. It’s the most natural perception in the world (voices come out of moving mouths, after all), yet a moment’s reflection would reveal the impossibility of this perception. Without fail, both I and my students perceive the scientist’s words as emanating from his or her moving mouth. Often the video clips feature scientists being interviewed. Indeed, the illusion is so compelling that we speak of the ventriloquist “throwing his voice”.ĭepending on how close we are to the puppeteer, this may represent a fairly small localization error (but a noticeable one, since we perceive a difference between where the ventriloquist’s voice is coming from when voicing the puppet versus voicing for himself.) Yet we are capable of making much more stunning errors in localization.įor example, I often show video clips in my classroom. The illusion can be very real if the ventriloquist is skilled the puppet’s voice is perceived to actually emanate from the puppet’s moving mouth. The ventriloquist may carry on a conversation with the puppet, speaking normally when upholding his or her part of the conversation, but hiding lip movements when voicing for the puppet. And yet probably many of us have experienced stunning examples of mis-localization: the ventriloquism effect.Ī ventriloquist, of course, is a performer who operates a puppet and also speaks for the puppet without moving his or her own lips. Even for sounds originating from off to the sides, we still do pretty good: within about 5-10 degrees. For example, having (hopefully) impressed you with our outstanding powers of auditory localization, consider for a moment our stunning incompetence in this very same area.įor sounds originating from directly in front of us, we can localize the sound source to within 2-4 degrees. One of the fun things about psychology and neuroscience, however, is how full of contradictions we are as humans. Based on microsecond time-keeping and split-second computations, humans can localize sounds with impressive accuracy even in confusing auditory environments. In my previous post, I described the rather amazing auditory abilities of human beings.
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