Sound is an invisible form of energy generated from vibrations. Sound waves propagate or repeat in a pattern as they travel across mediums. Sound can travel through air, water, even some solid surfaces like walls.
Make your voice high and then low – did you notice a difference in the vibration? That difference has to do with how fast the vibrations are happening. The speed of the sound wave is the frequency but the sound that frequency produces is called pitch.
When an object vibrates, so does the air around it. Sound and music are parts of our everyday sensory experience. Just as humans have eyes for the detection of light and color, so we are equipped with ears for the detection of sound.
Sound waves go on a bit of a journey for our brains to identify or hear a sound. From the outside of your head sound travels inside your skull before nerve impulses send a message to the brain.
- Ear lobe: Your ear lobe and outer ear help direct and funnel the sound waves into your ear.
- Ear Canal: Is a warm, moist, dark tunnel that goes into your head. The sound waves travel down this tunnel.
- Ear Drum: Is at the end of the ear canal. Scientists call this the tympanic membrane. When the sound waves hit the ear drum it vibrates. Without the ear drum you would not be able to hear!
- Ossicles: A tiny chain of bones (the smallest in your body). The vibration travels from the ear drum and vibrates this chain of bones (the hammer/malleus, anvil/incus, and stirrup/stapes).
- Cochlea: Looks like a spiral and the very last bone in the ossicles knocks on the cochlea, which vibrates the liquid inside and translates it into nerve impulses.
- Auditory Nerve: At the end of the sound’s journey is this nerve. It picks up the vibration information and communicates it to the brain. The brain interprets the information, so you know if a dog is barking, your mom is calling you, or if a train is going by.
Besides our own voices, humans, throughout
history, have created instruments to make sounds and music for enjoyment and
communication. Instruments work by creating vibrations in a variety of
ways. You can play an instrument by manipulating the pitch or note you
are generating with the instrument.
Basically, instruments create vibrations via
the plucking of strings, hitting a surface (percussion), vibrating air in a
tube (horns), or vibrating a small piece of wood called a reed (woodwinds). You
can see each category expressed in an interesting way in cultures all over the
HTHT @ Home Science Experiment to make your own harmonica: