Book review of Seth Horowitz

Seth Horowitz:
"The Universal Sense" (2012)
(Copyright © 2014 Piero Scaruffi | Legal restrictions )

The US neuroscientist Seth Horowitz has written an intriguing book about sounds and the way animals use them. There are so many enlightening meditations hidden in these chapters. We never live in silence because the world is constantly full of sounds. And those sounds include important information, that life has learned to use to its advantage. Human hearing is just one specific kind of "vibration detection". Other species have their own ways of "listening" to the planet. Horowitz speculates that, when mobile life was born with the advent of cilia, those cilia also evolved into sensors capable of detecting motion around them at a distance (for example, in water). At some point after becoming capable of interpreting sound, life also began to "make sound". Because we know that other members of our species and other animals interpret sounds, we can make sounds that will affect their behavior. Sound became a two-way process, i.e. a communication tool, something that vision cannot be (we cannot emit light the way we emit sound, although one could argue that gesturing and making faces are a visual way to communicate). The effectiveness of communication must have triggered a rapid evolution of both sound making and sound interpreting organs. The more sounds an animal can make, and other animals of the same species can understand, the more sophisticated their behavior can be. Life became increasingly "noisy". Horowitz calls it "an acoustic ecology". All this life intent on making new sounds literally changed the sound of the planet, that used to be due only to the sounds of inanimate matter (such as rain and rivers). Humans have been particularly good at filling their environment with new sounds that didn't exist before (from phone ringers to automobile exhausts). Later in the book Horowitz also points out that vision is a slow process: light travels fast, but processing visual signals takes a long time inside the brain, whereas it takes only a few milliseconds for us to identify a sound and its direction.
The original sound is distorted by innumerable little factors, such that what we eventually hear is just a "reverberation" of it. Spaces and places influence how we hear a sound. Nonetheless, we are often capable of recognizing the origin of a sound under confusing circumstances. Horowitz points out that we can even identify a friend from the sounds of her footsteps.
A chapter on fish and frogs ultimately shows that precious information on how to restore hearing in aging humans (once lost, auditory cells in humans, and all other mammals, cannot be regenerated) could be elicited from fish and frogs, if we could only figure out how the tadpole rewires its brain in two days and how the bullfrog regrows its auditory nerves. Bats are even more amazing because their life depend on high-frequency sounds and live a relatively long life: high-frequency sounds are precisely the first sounds that aging humans have trouble hearing.
The longest chapter, "What Lies Below", is also the most technical, dealing with the neuroscience of human hearing. Unfortunately, if i understood correctly, the conclusion is that we don't know how the mind hears. What is clear is that sound has an emotional quality that transcends syntax and semantics: the tone in which we say something delivers a strong emotional content. Write it down and you need to use a lot of emoticons, or a lengthy explanation, for what naturally takes only an intonation to deliver.
The mildly annoying part of the book is when Horowitz takes detours in autobiographical anecdotes. My initial reaction was that he should rather stick to the science, which is fascinating enough. But then i realized that the book was not only about the neuroscience of hearing but also about a lot of other topics related to music. The chapter on "Who Can Define Music" introduces solo percussionist Evelyn Glennie, who happens to be mostly deaf, and who basically plays the room, not just her instruments, and then to the various popular theories of how music can "heal" and enhance intelligence. This discussion leads naturally to a discussion on how marketing departments try to "hack" our brains and makes us buy things we don't need: they do it by using music.