Posts Tagged ‘bats’

Sonic Wonderland by Trevor CoxSonic Wonderland: A Scientific Odyssey of Sound, Trevor Cox (Vintage 2015)

This book is a good example of “think ink”: it makes you think about familiar things in a new way. Sound is familiar to almost everyone, but it’s a much more complex phenomenon than most people realize. Only part of it takes place in the air; there’s a lot going on in the brain too. Trevor Cox looks at both sides of sound. And more sides than that, because it’s a three-dimensional phenomenon. And four-dimensional: time is involved.

That’s most obvious with echoes, which Cox explores in chapter 1, “The Most Reverberant Place in the World”:

I like to play a game with my fellow acousticians: guess the reverberation time. They usually pick an acoustically outrageous number, maybe 10 or 20 seconds. Even so, they always guess far too low. At 125 hertz, the reverberation time was 112 seconds, almost 2 minutes. Even at mid-frequency the reverberation time was 30 seconds. The broadband reverberation time, which considers all frequencies simultaneously, was 75 seconds. I called Allan over to give him the good news. We had discovered the world’s most reverberant space. (ch. 1, pg. 57)

And where is that? It’s the “oil storage complex at Inchindown, near Invergordon”, in Scotland. Huge tanks, in other words, that were built in the 1930s to store oil for a nearby naval anchorage. They’re “dug deep” into a hillside and now are decommissioned, so they’re empty, dark and rarely visited. But, as Cox discovered, they’re also acoustically fascinating: “Never before had I heard such a rush of echoes and reverberation” (pg. 55).

As professor of acoustics at Salford University, Cox is well-equipped to investigate and analyse places like that, but sound is too big a subject for any individual to understand everything. This book discusses a startling range of animals, objects and acoustic phenomena: bats, moths, barking fish, claps, bells, whispering galleries, echoes that conduct conversations, musical roads, icosidodecahedral loudspeakers, wave organs, abandoned radomes, waterfalls, singing sands and ringing rocks. Last and least, it discusses silence:

The ear is exquisitely sensitive. When perceiving the softest murmur, the eardrum barely moves. For the quietest sound that a young adult can hear, the eardrum vibrates by less than one-tenth of the diameter of a hydrogen atom. Even in silence, tiny vibrations of molecules move different parts of the auditory apparatus. These constant movements have nothing to do with sound; they stem from random molecular movements. If the human ear were any more sensitive, it would not hear more sounds from outside; instead, it would just hear the hiss generated by thermal agitation of the eardrum, the stapes bone of the middle ear, and the hair cells in the cochlea. (ch. 7, “The Quietest Places in the World”, pg. 209)

I’m not sure about “one-tenth of the diameter of a hydrogen atom”, which seems very small, but measurement is certainly essential to acoustics. Modern instruments can turn sound into shape, which is appropriate, because sounds are essentially shapes. You might call them sculpted air, just as waves are sculpted water. And light is sculpted energy. The parallels between light and sound weren’t obvious to the ancients, but they explain lots of things, such as why some frequencies of sound, like some frequencies of light, can travel further than others through air or water or stone.

And the visual phenomenon of iridescence has its acoustic equivalent: sonic crystals, which “reflect some frequencies intensely, mimicking the iridescence of butterfly wings” (ch. 8, “Placing Sound”, pg. 256). Unfortunately, Cox says that the sound is “unpleasant”. But this is a new field and perhaps beauty will be born in time. Ugly or exquisite, thunderous or threnodic, sound is a fascinating subject and this book will open both your ears and your mind to its wonders and weirdness.

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Life: Extraordinary Animals, Extreme Behaviour, Martha Holmes and Michael Gunton (BBC Books 2009)

Probably the best BBC book I’ve seen: the beautiful photographs and the enlightening text complement each other perfectly. It’s not advanced biology, with equations and game theory, and it doesn’t give scientific names. But it does include some recent discoveries, like the rehabilitation of the Komodo dragon. If that’s the word:

The tissue damage from the bite is not enough to kill. Until recently, it was thought that bacteria in the dragon’s saliva poisoned its prey. But it has been shown now that the dragon, like some snakes, has venom, making it the world’s largest venomous animal. (ch. 5, “Frogs, Serpents and Dragons”, pg. 134)

The Komodo dragon has become more frightening. And also more interesting. But the book isn’t only about big and frightening: it’s also about strange and beautiful, like:

A tall Gersemia soft coral bending over to sweep tiny animals from the sediment. It does this when there isn’t enough food in the water for its polyps to trap. Once it has consumed everyting in a circle around itself, it will detach from whatever it is holding onto and crawl to a new spot. (ch. 1, “Extraordinary Sea Creatures”, pg. 39)

Germesia soft coral
That’s in very cold water under “the ice in McMurdo Sound, in Antarctica’s Ross Sea”, as part of an “ancient, isolated and utterly unique community” of marine life: there are also sponges, starfish, proboscis worms and sea-urchins. The Gersemia looks both beautiful and graceful, bowing to the sediment like a jewelled and mobile tree, but those are human terms for an organism that probably isn’t even conscious. And all of those organisms that are conscious, like the mammals in the final three chapters, aren’t aware of how they look to us. Natural beauty – and its absence – aren’t designed for us, but the aesthetics of animals is an interesting topic.

Television wants powerful images and this book reproduces them from the series, like the “lioness charging across a river in the Okavango” on page 228. But I think the static image must be more powerful than the mobile one: the photograph freezes the chaos of splashing water and the pale gold perfection of the lioness herself. She wears a look of immense concentration and purpose and I’ve rarely seen a better example of the power and beauty of the big cats. On page 219, there’s an image of one of the big cats’ greatest enemies. It’s also powerful, but in a different way: “a yawning spotted hyena revealing a perfect set of teeth, specialized for cutting, tearing and grinding.” Hyenas are interesting but not attractive. Big cats are both, from the charging lioness to the cheetahs on pages 231-5 and the alert lynx on page 237.

So why is the cat-family, big and small, generally much more attractive than the dog-family? And why are bats often so grotesque? The bulldog bat sweeping up a fish on pages 242-3 has a flat snarling face, ginger fur, taut, veined wings, hook-like hind claws and what looks like a small dangling penis. Birds are often very attractive. Why not bats? Their hairiness and leathery wings are part of it, as are their faces, which are adapted for sonar and eating, not for appealing to human beings.

And then we come to the primates in the final chapter. Now we’re getting closer to home. The faces of each species has a distinct effect on humans, from the endearing spectral tarsier to the choleric red uakari and the melancholy macaque. And chimpanzees look more intelligent than gorillas. Their faces haven’t evolved for our eyes, but they trigger mechanisms in our minds all the same.

So do the insects, birds and fish earlier in the book. And the plants in the single chapter devoted to them, like the bamboo and the dragon’s-blood tree. Colour and line: beautiful and ugly, attractive and repulsive. But all of this bio-aesthetics is interesting and all of it’s governed by natural and sexual selection. And behind it all is Mathematica Magistra Mundi, Mathematics Mistress of the World, from the circle swept by a soft coral on the floor of an icy ocean to the pattern of veins in a bat’s wing and the stripes in a tiger’s pelt.

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