Every single human voice has a slightly different mix of its basic pitch, undertones and overtones.  Added together and they give each voice a distinctive quality – what musicians call the timbre of an instrument, only for the voice.  You are so good at hearing the timbre of human voices that you can identify every human voice you know – typically hundreds –  in an instant, without being aware that you’re doing any work, and without consciously hearing the undertones and overtones.  You just blur them all together in “John’s voice,” or “Jane’s voice.”

It’s an amazing feat when you think about it.  It’s the unconscious mind at work, running mental circles around the conscious mind, preparing life for it, making it easy, teeing up voices, patterns, and memories at unbelievable speeds, all before the conscious mind even knows something is about to happen.  Milliseconds before, for the most part, but still.

In the digital era, all of this went horribly wrong.

The engineers working on telephones cut out most of those undertones and overtones, which is why voices don’t sound quite as distinctive on the phone, but still distinctive enough to be told apart, usually, by the unconscious mind.  So far, so bad.

But here’s where it gets really interesting.  It turns out that the emotions in human voices are carried by the undertones, so that when you cut out some of that spectrum of sound, you take the emotion out of voices.  It’s why audio conferences are so boring.

And when you realize that you make decisions based on your emotions, then you begin to see that audio conferences, and VOIP calls, and most computerized phone systems, and most computer video systems based on the same bandwidth compression – all are rendered both uninteresting and difficult to think about usefully.

What about video – if you can see people in the virtual world, does that help?

And the answer is, yes, of course, video helps somewhat, but it brings its own challenges.  Why do most people find video such hard work?  Why do people tend to shout over video conferences even when everyone tells them they can hear just fine?

It turns out that your unconscious mind manages yet another incredible feat while you’re talking face to face with someone else.  We tend to move closer to people, ideas, and things we like, and away from people, ideas, and things we don’t like.  It’s a body language signal, in fact, that most people are not very good at disguising.  We rear back our heads, for example, when we are hit with an offensive smell, person, or idea.

Now, your unconscious mind not only notices visually that the people around you are moving back and forth as a gauge of their moods, but it also notices the small changes in the air movement caused by those motions.  When you’re watching someone on a video conference, your unconscious mind is looking for those clues, not getting any, and therefore deciding that the other person is further away than they actually are.

Hence the shouting.  And hence also people feel that video calls are hard work.  They are to face-to-face communications as tin can telephones and string are to real phones.  (And remember why phones are hard work, too.)

The digital world, much of it, is in effect two-dimensional when what our minds crave is three dimensions.  The audio stream is reduced.  The emotions are blocked or deracinated.  Video is in fact two-dimensional and lacking sensory input.  Email and text lack tonal and audible clues to intent.  In system after system, in short, the bandwidth is reduced in ways that we can’t easily notice, and that have to do with emotion and the essential, core human thinking processes.

And that’s also in part why we find digital communications such hard work.  They feel like they should be easy, and being mostly frictionless, they are easier in some ways.  But in unconscious ways, in ways that we can’t easily appreciate, they are sorely lacking, and we find it hard to compensate as a result.

The digital world makes much, much worse the one area humans really reign supreme – the power of our unconscious minds to absorb information, recognize patterns, and make instant predictions about the future that help keep us alive.

This post is adapted from my new book, Can You Hear Me?, due out from Harvard in October.  You can pre-order it here.