This week we are learning about "hearing". The senses are how we get information about the world around us to our brain. Each sense is based on the sensor (sense organ, sensory cell type) which responds to a specific kind of stimulus, and the region of the brain that responds to it. With respect to hearing, the organ is the "ear" and the stimulus is "sound waves".
Sound
John C wants to know "What is sound?" Jack S wants to know "What is volume?"
John C wants to know "What is sound?" Jack S wants to know "What is volume?"
We didn't watch this video, but we it covers the same information. We did the activity in the video to see how a rubber band vibrates to create sound. In the activity they could see how pulling on the rubber band lightly would create a softer sound and pulling on it harder made a louder sound. Stopping the vibrations, stopped the sound. | Sound is a type of energy made by vibrations. When any object vibrates, it causes movement in the air particles. These particles bump into the particles close to them, which makes them vibrate too causing them to bump into more air particles. This movement, called sound waves, keeps going until they run out of energy. Source |
We watched parts of this video which shows sound waves.
Hearing
Marcus wants to know "What causes hearing?"
Marcus wants to know "What causes hearing?"
We didn't watch this video, but we covered the same information. The folds of the outer ear, the pinna, has evolved to enhance sounds with a pitch that is typical of a human voice. It enhances it up to 100 times and leave other pitches untouched. The sound waves are directed through the ear canal where the vibrations move the ear drum. The ear drum causes the three smallest bones in the human body (hammer, anvil, and stirrup) to move. The stirrup hits the cochlea which is filled with fluid. Thus causing transferring the sound wave energy from air to fluid. The sound wave is 22 times greater where the stirrup hits the cochlea than at the ear drum. As the wave move through the cochlea, it uses 17,000 hair cells to transmit signals to the brain. | |
After we walked through each part of the ear, we watched this video to "put it all together". | |