Science of Hearing- V ( Hearing in Vertebrates)

Hearing in Mammals

Mammals are the highly evolved animals. They are warm blooded, endothermic animals. They can regulate their body temperature according to the temperature of the environment. Therefore they can live in any part of the earth. They give birth to their young ones alive. They feed their young ones by the milk secreted in the mammary glands.   They have very well developed brain which can recognise and understand different types of sensory activities. They have well developed sense organs. They can communicate with their group members and understand the sound created by their enemies.

Most of the mammals have well developed sensory organs. Their ears are developed very well. The shape and size of their ears depends on the ecosystem where they are living. They have external ear which helps in collecting sound waves and amplifying those waves.

How do cats hear?

Cats have excellent hearing capacity. They can detect broad range of frequencies of sound. Cat’s hearing is extremely sensitive and is the best among mammals. Their hearing range is between 500 Hz to 32 KHz. Their sensitivity is further enhanced by the cat's large movable outer ears, which amplify sounds and helps the cat to sense the direction from which a noise is coming.

How do Dogs hear?

Dog’s hearing range varies between 40 Hz to 60 kHz. Their hearing capacity depends on their breed and their age. When dogs hear a sound, they will move their ears towards the direction of sound to maximise reception. In order to achieve this, the ears of a dog are controlled by at least 18 muscles, which allow the ears to tilt and rotate. The ear's shape also allows the sound to be heard more accurately. Many breeds often have upright and curved ears, which direct and amplify sounds. They can hear higher frequency sounds than human beings.

How do rats hear?

Rats can hear ultrasound.  The range of the rat's hearing is around 200 Hz to 80 or 90 kHz. They have large ears in comparison to their bodies. They hear higher frequencies of sound than human beings. They do not hear the lower frequencies of sound that humans can. 

How do Elephants hear?

Elephants have good hearing, detecting sounds as low as 14 to 16 hz (human low range: 20 hz) and as high as 12,000 hz (human high range: 20,000).

Elephants frequently use infrasonic sounds, which are sounds emitted below the human hearing range, in long—distance communication. Research has shown that elephants are capable of recognizing calls and voices of particular individuals from 1 to 1.5 km (0.6-0.9 mi.) away.

The ears of the elephant are used to funnel in sound waves from the environment, but elephants don’t just hear with their ears. They astonishingly, hear with their feet. Elephants can hear warnings sent through the ground from other elephants, received by pressure sensitive nerves in the pads on their feet.  The stomps transmit the warnings via vibration. But it’s at a frequency through the ground that other elephants are uniquely genetically engineered to receive. They are able to factor in typical seismic vibrations and determine via these receptors. Thus elephants can hear the movement of the Earth prior to the onset of Earth Quakes.

How do we, human beings hear sounds?

Sound waves travel into the ear canal until they reach the eardrum. The eardrum passes the vibrations through the middle ear bones into the inner ear. The inner ear is shaped like a snail and is also called the cochlea. Inside the cochlea, there are thousands of tiny hair cells. Hair cells change the vibrations into electrical signals that are sent to the brain through the hearing nerve. The brain tells us that we are hearing a sound and what that sound is.