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Applying knowledge of pitch and volume to see how musical instruments are designed.
Why does a tiny bird-like flute sound so high, while a giant tuba sounds like a low, growling bear? The secret isn't magic—it's physics!
Quick Check
If you press your finger down on a guitar string to make the part that vibrates shorter, will the pitch get higher or lower?
Answer
The pitch will get higher because shorter strings vibrate faster.
Drums work by vibrating a surface called a 'drumhead.' The size of the drum changes the sound because of the amount of air inside. A small drum has a small amount of air that can vibrate very quickly, leading to a higher, 'snappy' sound. A large drum, like a bass drum, has a lot of air and a large surface. It takes more energy to move all that air, and it moves more slowly, creating a deep, low pitch. This is why a tiny hand drum sounds like a 'tap' while a giant drum sounds like a 'boom!'
1. Look at a violin. It is small and has short strings. It plays very high notes. 2. Look at a cello. It looks like a giant violin with very long strings. 3. Because the cello strings are much longer, they vibrate slower, making the cello's sound much deeper than the violin's.
Quick Check
Which would have a lower pitch: a tiny toy drum or a large trash can used as a drum?
Answer
The large trash can would have a lower pitch because it is bigger and holds more air.
1. Hold one end of a plastic ruler firmly against the edge of a desk so the other end sticks out. 2. Gently flick the end of the ruler. It moves a little bit and makes a quiet sound. 3. Pull the ruler down much further and let go. It moves up and down a lot more, using more energy, and makes a much louder sound.
Imagine you are making a flute out of plastic straws. 1. To make a 'Do-Re-Mi' scale, you must cut the straws into different lengths. 2. The longest straw will be your lowest note (). 3. To make the next note higher, you must cut the straw shorter (). 4. To make the flute louder without changing the straws, you must blow more air (energy) into them!
If you want to make a string instrument play a lower note, what should you do?
Which of these determines the volume of a sound?
A large bass drum usually has a higher pitch than a small snare drum.
Review Tomorrow
Tomorrow, try to explain to a friend why a rubber band makes a higher sound when you stretch it tighter and make the vibrating part shorter.
Practice Activity
Find three objects at home (like a pot, a glass, and a box). Predict which will have the highest pitch when tapped, then test your theory!