Friday, June 06, 2008

Going gaga over phonetics

(Nancy Friedman's recent post reminded me of the McGurk Effect.)

A long time ago I started to doubt that [m] and [n] could possibly be different sounds. I would close my mouth and make the mmmmm sound then I would put my tongue on the alveolar ridge. That's really not as dirty as it sounds. I would open my mouth trying to make the transition so smooth that the change in sound was imperceptible. I figured I was probably succeeding.

My parents were worried about me.

One of the reasons I went into linguistics was my fascination with stand-up comedians. Especially those that did impressions and impersonations. As a kid I was also taken by ventriloquists. Not kidnapped -- just amused.

It all seemed like some sort of magic trick. How could they say [p]s and [b]s and [m]s and even [f]s without using their mouths? The [f]s were easier for me to accept because air quickly forced between both lips sounded a lot like the puff between lips and teeth. But those others had me stumped.

In fact there is a difference between [m] and [n] and it has to do with the amount of space allowing the sound to resonate in your mouth. But it's a slight difference and it's mostly context and the interaction with surrounding sounds that allows us to perceive it.

And ventriloquists can count on our eyes to influence what we hear as well. [added later: That may seem counterintuitive because the ventriloquist isn't showing the correct articulation. But in the ventriloquist's case we're expected to ignore the performer's face and concentrate on the dummy's mouth movements. That in combination with ambiguous articulation and reliance on clues such as familiar words and likely interpretations. E.g.: We rarely hear such clusters as thl- so in a word like thlag we are more likely to hear it as flag especially in a sentence in which we expect to hear flag.]That's the McGurk Effect (the influence of visual cues on aural information). Watch this video. (downloaded from Arnte's sound site)

What sound is he making? Even when Buffy tries really hard to listen 'objectively' and even after she has listened while looking away and agreed that he's saying [baba] Buffy cannot but hear it as [dada] while watching. Even if she's just looking at his eyes.

The man you see in the video is articulating [gaga] but most people hear it as [dada]. We 'hear' [dada] because the phonetics of [dada] (alveolar stop) are closer to [baba] (bilabial stop) but look more like [gaga] (velar stop). So our perception splits the difference between the sound we hear on the audio track and the image we see in the video track.

The following isn't actually the McGurk Effect because the sound actually is changing as you hear it. But this is one of those tricks I used to do when I was a kid playing around with sounds. I figured that since I said [w]s by almost closing my mouth I could approximate that same effect using my hands. I would hold my mouth in an exaggerated 'aaah' position and use my hands instead of my lips to create a 'labial' approximant as an onset and a coda.

I've never performed this for anyone. And since no one reads this blog I'm willing to post a quick video of it.

Buffy's worried about me.


  1. I tried the W trick out, and my dog went completely nuts.

  2. That McGurk shit is fucking awesome.


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