Tag: hearing

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Why Don’t Birds Have Ears?

Why Dont Birds Have Ears?
Someone asked, “Why don’t birds have ears?” Actually, birds do have ears. What they don’t have is what biologists call “auricles” and zoologists call “pinnas.” Those are the things that stick out from the heads of people and most mammals and that we usually call “ears.”

The most critical ear parts are not outside but inside the head. Birds have those parts. Most birds have excellent hearing in spite of not having visible “ears.” The ear openings are not visible because they’re covered with feathers. The feathers are often designed to channel the sounds into the ear canal, just as our auricles are.

Parrots have such good hearing that before the invention of radar they were used to detect the engine hum of distant enemy airplanes. They would squawk a warning of danger. Migrating birds use sounds along with other clues to find their destination. Homing pigeons listen for sounds to help guide them to their familiar roost.

Another design factor to consider is wind resistance. What would happen if birds had ears that stuck out from their heads? It would slow them down in flight. Also, consider the noise you hear when facing into the wind on a blustery day. Without the pinnas, birds don’t pick up so much wind noise when they’re flying.

So now you know the answer if someone asks, “Why don’t birds have ears?” Don’t worry about not seeing ears poking out from a bird’s head. It’s just another indication of good design by the Master Designer of life.
–Roland Earnst ©2019

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Design in Hearing

Design in Hearing
One of the amazing features of animals is design in hearing. Humans can hear sounds between 20 and 20,000 vibrations per second (Hertz). That range allows us to communicate through the air and enjoy music. Various animals can hear sounds in different parts of the frequency spectrum.

Dogs can hear frequencies higher than 20,000 Hertz. We call these sounds ultrasonic because they are above the frequencies we can hear. We use ultrasonic sounds for examining the organs inside the human body. We use it to view unborn babies inside their mother’s womb. Ultrasonic sound has uses such as cleaning of jewelry or other items. But we can’t hear it. The ability to hear ultrasonic sounds gives dogs and other animals a defense advantage. Try to sneak up on a dog. If you open a door or step on a floorboard creating an ultrasonic squeak which you can’t hear, the dog will hear and know that you are coming.

Elephants, whales, and other large animals can hear low frequencies and use them to communicate over many miles because low frequencies travel more efficiently through the ground or water. But it isn’t just large animals that use these subsonic sounds. Some small animals, like moles, can also hear low frequencies since those sounds travel well through the ground. If a mole communicated through sounds we could hear, finding and killing them would be easier for their predators and us. Because they communicate at frequencies below 20 Hertz, they are not easily detected by animals above the ground.

Design in hearing also applies to frogs, snakes, and many insects that can also hear very low or very high frequencies allowing them to communicate with others of their kind without detection by different species. Different creatures use various portions of the audio spectrum. If a creature gives off sounds that its predators can hear, they will literally be “dead meat.”

The world of sound rings out loudly the incredible design of the Creator who gave various creatures the ability to hear the sounds they need to hear. We can be thankful that God gave us the ability to hear the beautiful sounds of music and the spoken voice.
–Roland Earnst © 2018

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How You Can Tell Where It Is

How You Can Tell Where It Is
When you look at something or hear it make a sound, have you thought about how you can tell where it is? How do you determine its direction and how far away it is? Studies of human sight and hearing tell us that two different systems are involved. One system works for sight, and another for sound.

Hold up a finger at arm’s length from your face. Close one eye and look at the finger and what is beyond your finger. Now switch eyes, and you will see that objects beyond your finger appear to move. When you look at a distant object, the brain receives two signals–one from each eye. Based upon how much the background seems to vary, your brain then computes how far away the object is. That’s how you can tell where it is because your brain combines both images to give you a distance perspective.

To locate a sound’s source, the brain gets a signal from each ear. The two signals arrive at slightly different times depending on the width of the skull and the direction of the sound. We cock our heads to take into account the angular location of the source, and the brain creates an auditory spatial map that pinpoints the sound. Your senses handle sound differently from sight because of the difference in speed of the two signals. Light travels at 186,000 miles (300,000 m) per second and sound travels at 1087 feet (331 m) per second. Your brain combines the object’s sound signals received by both ears, and that is how you can tell where it is.

All of this is amazing enough, but researchers at the Max Planck Institute for Biological Cybernetics in Tubingen, Germany, and Queen’s University in Kingston, Ontario wanted to learn more. By using visual tests on a barn owl while monitoring its brain activity, they found that different nerve cells respond to “specific angular differences.” The barn owl used auditory methods with its vision to give it a three-dimensional map of the area. In that way, the owl has an instant picture of where to fly to get the most unobstructed path to its target. The director of the institute said, “We speculate that the brain uses similar algorithms to solve similar problems” such as matching problems.

We take so much for granted about how our basic senses work. As we have said before, David got a small understanding of this which caused him to say in Psalms 139:14, “I will praise you, God, for I am fearfully and wonderfully made. Marvelous are your works.”
–John N. Clayton © 2018