Depending on the shape and position of Dino's ears, it may be hard to believe those big, floppy ears are excellent hearing tools. However, his range of hearing is twice yours. Don't feel bad; your pup's ears have a lot of work to do and compensate for his poorer vision.
To get an understanding of how Dino hears pitch, it's helpful to know the difference between sound and frequency. Sound is the movement of longitudinal waves hitting the ear. Frequency is the number of sound waves per second, measured in hertz, or Hz. Frequency is heard as tone and pitch, and the lower the frequency, the lower the pitch. The roll of thunder has a low pitch and a long wavelength, and is about 20 Hz. The roar of a jet engine has a high pitch and short wavelength, and is about 10,000 Hz.
Humans hear in a frequency range of 20 to 20,000 Hz. Despite their overall superior hearing, dogs don't hear to the low levels humans do. Some dogs can hear as low as 40 Hz, while others can't hear sounds below 60 Hz; the lower limit depends on the breed and age of the dog. Dino's hearing does outshine yours on the upper end of the frequency range. In fact, he can hear at twice the range you can. Louisiana State University estimates dogs can hear up to 45,000 Hz. The sound of a vacuum cleaner can be loud to us, however when your pup runs away from it, he's probably fleeing the sound of a high-pitched noise you can't hear.
Erect or folded, a dog's ears are positioned on his head for maximum receptiveness. Dino's outer ear, known as the pinna, is controlled by more than a dozen muscles. Those muscles work to move his ear around toward whatever sound catches his attention. Dino's ability to change the shape and direction of his ear transmits sound to his eardrum. His long ear canal is an effective funnel to his middle ear.
After Dino turns his attention and his ears to the noise that interests him, the sound travels to his middle ear. The eardrum and a small air-filled chamber containing three bones -- the hammer, anvil and stirrup -- reside in the middle ear. The size of the chamber and the stiffness of the bones affects how sound is transmitted. In Dino's case, the configuration contributes to his higher hearing range. Dino's inner ear plays its part in his extended hearing range. A dog's cochlea makes 3 1/4 turns; this important hearing organ is filled with hair cells that pick up auditory vibrations. No one knows definitively, but it's believed that the longer cochlea, and the additional hair cells, help extend a dog's hearing range.
- Whole Dog Journal: Structure of the Canine Ear
- Responsible Dog and Cat: Canine Senses
- The Merck Manual for Pet Health: Ear Structure and Function in Dogs
- Dog Breed Info Center: Understanding a Dog's Senses
- Mad Sci Network: How do Dogs Hear a Bigger Range of Frequencies than Humans?
- Stanley Coren, How Dogs Think: Understanding the Canine Mind
- Louisiana State University: Deafness: How Well Do Dogs and Other Animals Hear?
- Mr. Murray's Science: Sound
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