Sound and music
Why do we see lightning before we hear the thunder? How do we amplify sound and how do we reduce it? How is it we can hear at all? Sound is all around us every day and it is important for students to understand how and why we hear in order to manipulate their surrounding environment.
Key concepts of sound and music
The activities in this topic are designed to explore the following key concepts:
- We hear sound with our ears.
- Our sense of sound is very sharp.
- Sound travels through air.
- Sound travels through water and solid objects.
- We use two ears to judge where sounds come from.
- Sound bounces off surfaces (echoes).
- Sound is caused by vibrating objects.
- Sound can vary in pitch (or frequency) and loudness.
- The pitch (or frequency) of sound is related to the speed of vibration of the sound source. The more vibrations per second, the higher the pitch.
- The loudness of sound is related to the size of vibration of the sound source: the larger the size of vibration, the louder the sound.
- Sound needs a material medium through which to travel.
- Sound travels faster through solids and liquids than through air.
- Sound is a travelling vibration that moves through a medium such as air, water or solid objects.
- Sound can bend around corners and spread out after passing through gaps.
- Objects have their own natural vibration pattern and can give a characteristic note when hit (or blown).
- Large or long objects vibrate more slowly, causing sounds of lower pitch (or frequency).
- Objects can be made to vibrate in sympathy with others that have the same pitch (or frequency).
- Sounding boards amplify sound, and are important in instruments.
- Vibrating strings form the basis of stringed instruments.
- Vibrating air is the basis of wind instruments.
Students' alternative conceptions of sound and music
Research into students' ideas about this topic has identified the following non-scientific conceptions:
- Students find it difficult to express a mechanism for how sound travels.
- The loudness and pitch (or frequency) of sounds are confused with each other.
- You can hear and see a distant event at the same moment.
- Hitting an object harder changes its pitch.
- In a telephone, actual sounds, rather than electrical impulses, are carried through the wire.
- Sound moves faster in air than in solids (air is 'thinner' and forms less of a barrier).
- Sound moves between particles of matter (in empty space) rather than matter.
- Sound can travel through space.
- In wind instruments, the instrument itself vibrates, not the internal air column.
- The pitch of whistles or sirens on moving vehicles is changed by the driver as the vehicle passes.
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