“The reason why we have two ears and only one mouth is that we may listen more and talk less.” – Zeno
Which tempo today?
Like many people, I love listening to music and can’t imagine living without it. I am listening to some jazz piano (Brad Mehldau) as I write this, with great melodies, but some unpredictability and spontaneity, which I hope will trigger some interesting and spontaneous ideas later in the article! I love Mozart too, much more structured and easy on the ear, although a lot of research on the “Mozart Effect” has failed to prove the specific benefits of his music. Much of the effect of listening appears to come from music’s ability to influence our mood. When we are happy and positive we are often much more productive and creative.
Mozart was certainly very creative, although he didn’t have the opportunity to listen to an iPod while writing scores. We all know that music strongly influences our moods: calming a troubled child, rousing a crowd or connecting a group of people to the same rhythm and vibe. For instance, playing faster music while working out has been shown to significantly increase the tempo of your exercise (which is why many use dance music while running or in the gym). Although this makes you work harder, something we tend to notice, it doesn’t feel as hard on your body when accompanied by the right music.
The digital (and mechanical) sense
Although our ears help us maintain balance, their most important function is help us hear the rhythm of life. While vision helps us to see where things are happening in the world, hearing helps us to understand when things happen, and gives us a sense of time and causality. Our hearing can make sense of frequencies as low as 20 Hz (one beat or event per second) and up to 20,000 Hz (1 beat per millisecond), helping us make sense of the order of events. As well as understanding temporal order, our hearing also helps us determine direction, distance and speed, through the difference in volume and timing of sounds reaching our left and right ears (in combination with vision). We can detect differences as small as 20 microseconds in timing between the ears and turn this into important information about where to check for threats and obstacles in the environment.
Ironically, especially for those who long to return to the age of the gramophone, sound has always been digital rather than analogue. When we sit in the cinema, film is typically shown at 24 frames per second, which appears to our eyes as a continuous display of images. If we listen to sounds at 24 clicks per second, we hear 24 clicks, and even up to four times this speed, clicks appear discrete and do not blur into continuous sound).
Hearing is very mechanical (or physical) in its function, stemming from the vibrations of bones and then hairs in our ears, which are converted into signals to the brain. These vibrations come from discrete events in the outside world, causing vibrations in the air around us – collisions, movements, explosions, breakages, bangs and other sounds associated with changes in the environment.
What is it like to be a bat?
Although Thomas Nagel’s essay “What is it like to be a bat?” discusses the problem of defining consciousness, humans actually possess many of the abilities of bats, although to a much lesser degree. While humans can detect sounds with frequencies up to 20,000 Hz, a bat can detect them up to 110,000 Hz, using the timing, energy and frequency differences between the sounds they emit and the sounds that return to learn about the shape, composition, location, size and distance of objects in their environment.
Amazingly, we all do this to some extent – make a ‘shhhhh’ sound with your mouth and then move your hand closer to your mouth and then further away and you will hear changes in the sounds based on interference between sound waves as they leave your mouth and bounce back from your hand. This the principle of the echolocation used by bats. Now imagine that you are running late for a meeting and trying to read the agenda before you arrive. You navigate your way to the meeting room through your office, avoiding obstacles and people as you move – amazing how you manage this isn’t it? Have you ever tried doing the same while listening to your iPod? Be careful if you try, as you will not be able to take advantage of one of your key guiding senses!
We often see with our ears. Why do you think car manufacturers have had to add ‘engine noises’ to silent running electric cars?
If music be the food of love
There is a close connection between music and words, and although many other animals communicate through sound, human speech has been enabled by some very specific changes to our biology. In most animals the larynx which produces sound is much higher in the throat, to make it safer to eat without choking. In humans, the larynx is much lower, to enable a greater variety of sounds to be produced – there is clearly an evolutionary advantage to producing language which outweighs the risks of choking to death on food.
Hearing is the first sense to develop in the womb, in the sense that the myelination (insulation) of neurons associated with hearing is completed before that of the other senses. Ears start to form from as early as from two months in the womb, and babies start to react to sounds from as early as four to five months before birth. We begin to respond to loud and sudden sounds as soon as we are born – turning our heads toward them – and from three to six months we start to recognise sounds and make them for ourselves, forming recognisable words at about one year old.
Language is a topic for a separate post, but we all have innate musical ability too, responding to frequency, harmony and rhythm. As early as four years old we can label music with ’emotional’ content. We can recognise standard musical intervals, even if not trained in music. Try singing (or humming if shy) the first two notes of “Somewhere over the rainbow” and I am sure that you will sing something very close to an octave. You don’t need to be a professional to understand what a musical interval is! Opinions differ as to when musical instruments first developed, but there is evidence from at least 5-6,000 years ago, and it’s likely that it was much earlier than that.
I hear you
As well as being the first sense to develop (before birth), hearing is also the first sense to awaken when we become conscious in the morning and the last sense we lose when we fall asleep at night.
For researchers and innovators, hearing is a crucial sense, and my parting advice is to listen for the silences as well as the sounds. Above all, hearing and listening are all about timing.
A Natural History of the Senses by Diane Ackerman (1991)
The Brain Book by Rita Carter (2009)
See What I’m Saying: The Extraordinary Powers of our Five Senses by Lawrence D. Rosenblum (2010)
Mind Hacks: Tips & Tools for Using Your Brain by Tom Stafford and Matt Webb
What is it like to be a bat? by Thomas Nagel in The Mind’s I edited by Douglas Hofstadter and Daniel Dennett