Nothing whatsoever to do with audio, this post.  Question:  How do you know when an Italian is speaking?  Answer:  His arms are moving!

That’s a stereotype as old as the hills, and one with a lot of truth to it.  The fact that people – of all nationalities – tend to wave their arms and gesture as they speak is something that has always fascinated me.  The fact that I do it myself, despite being stolidly Anglo-Saxon, fascinates me just as much.  I find this aspect of human behaviour endlessly amusing.  For example, what is the purpose of gesturing exorbitantly while talking on your cell phone?  Why do I do it myself from time to time?

This morning, while working out on my cross-trainer, I think I came up with a crazy insight, and I thought I would share it with you.  On the TV set was a travelogue show.  The host was taking a leisurely stroll with a guest, discussing the history of Buenos Aires, as it happens.  The guest was doing most of the talking.  At the beginning his arms remained at his sides.  Then they began to gradually lift in front of him as he spoke, and finally began to adopt mild gestures.

I considered the mechanics of walking, talking, and gesturing.  What else is there to do when you’re stuck on a treadmill?  Lets start with talking.  In order to talk, you need to establish an overpressure in your diaphragm to drive the vibrations in your vocal chords.  The process of tensing your diaphragm involves tensing your abdominal muscles.  Try saying something out loud right now, and note how your diaphragm and abs both tense up.  When you are standing up, and also when you are walking slowly, your abdominal muscles are also part of the process of staying in balance.  They will be more tense, in general, than when you are sitting down.

So now imagine you are standing up, maybe even walking, and decide you are going to say something.  The first thing that happens is that your diaphragm tenses up to supply an overpressure.  This requires your abs to tighten slightly.  The tightening of your abs causes your upper body to want to bend slightly forward.  But you don’t want to tip forward, so your autonomous nervous system automatically compensates by raising your arms in front of you.  The angular momentum of your arms rising in front of you counterbalances the angular momentum of your upper body bending forward, and this balance means that you don’t tip over.

Now you start to actually speak.  This involves temporarily reducing the overpressure in your diaphragm to allow a controlled release of air through the vocal chords.  The reduced overpressure is accomplished, at least partially, by releasing the tension in the abs.  This then releases the forward bend in the upper body.  The raised arms now need to begin to lower again to provide the angular momentum to counterbalance it.

So here is the summary of what I have just described.  When a person starts the process of speaking, his arms first come up.  With each utterance the arms gesture forwards again, and in the pauses between utterances come back up again.  When the speaking is over, the arms can come back down.

What about the TV guest in Buenos Aires?  Well, I think that it all boils down to your core body strength and endurance.  If you are in good shape, and particularly if your core is in good shape, your body is less likely to tilt in response to a slight tightening of the abs.  Your back and other core muscles will tend to compensate automatically.  But if not, then as you stroll slowly along, chatting as you go, your abs are being lightly exercised, and after a while your core muscles will gradually tire, and you will need to use your arms to assist.  This is what happened to the Argentinian, who did not give the impression of being particularly buff.  At the start of his short stroll, he needed no arm assist.  Then, as he tired, his arms would raise – barely so – as he spoke.  By the end of the chat, his arms were all the way up, and he was gesturing with each utterance.

My thought is that the root of gesturing as we speak – which is common to all cultures and not just Italians – must lie in some sort of bio-mechanical response such as this.  I thought that was a pretty cool idea.  Any anthropologists reading this?