Where Sounds Come From
FoundationSounds come from vibration; the bigger the vibration, the louder the sound; sound bouncing off a wall is an echo.
- Vibrating objects make sounds.
- When vibration stops, the sound stops.
- The bigger the vibration, the louder the sound.
文體小知識：記敘文把探究過程像講故事一樣記下來。這一篇帶你敲敲鼓、摸摸喉嚨，一步一步找出聲音的來源。
§Text Passage
1In music lesson the drum goes boom, the class song and footsteps in the corridor mix together. Where do sounds come from? Behind every sound hides one common secret — vibration. Hunting for the source of a sound is as much fun as being a detective.
2Strike a drum: the drumhead immediately shakes up and down, booming; when the booming stops, the drumhead stops too. Touch your throat gently as you speak and you can feel your vocal cords quivering; pluck a rubber band and it swings back and forth while humming. When something vibrates there is sound; when the vibration stops, the sound stops too.
3How do we make the drum louder? Strike harder! The bigger the drumhead's vibration, the louder the sound; strike lightly and the small vibration gives a soft sound. Loud speech means big vibrations of the vocal cords, and quiet speech means small ones — exactly the same rule. The size of the vibration decides how loud a sound is.
4Shout at a mountain or in a big empty hall, and a moment later you hear your own voice again — that is an echo. Like a ball, sound bounces back when it hits a wall or a cliff. In a room the walls are close, so the echo returns at once and mixes with the original sound, and we hardly notice it.
5Be a sound detective: rest your hand lightly in front of a radio speaker to feel the vibration, sing in the bathroom and listen for the echo, and tap a little cup with different strengths to compare loudness. Remember to protect your ears: cover them or leave very noisy places, keep earphone volume moderate — sounds that are too loud for too long damage hearing.
1Summary 重點摘要
Sounds come from vibration; the bigger the vibration, the louder the sound; sound bouncing off a wall is an echo.
2Vocabulary cards Vocabulary
What vibrating objects make and our ears hear.
Quick back-and-forth movement, like a shaking drumhead.
How loud or soft a sound is, decided by the size of the vibration.
A big-vibration sound, like a drum struck hard.
A small-vibration sound, like a drum tapped lightly.
Sound bouncing back after hitting a wall or cliff.
A percussion instrument; its shaking head booms.
The part in the throat that vibrates to make our voice.
A stretchy loop; pluck it and it vibrates with a hum.
The ears' ability to hear; it needs protecting.
3Step by step Steps
- Step 1: Discover how sound and vibration connectRun a little experiment: put some beans on a drumhead and tap the drum — the beans jump at once while the drum sounds; when the sound stops, the beans stop too. The drumhead was vibrating, and vibration makes sound. Try more: touch your throat gently while speaking and feel it quivering inside; pluck a rubber band and see it swinging back and forth with a hum; when it stops, the sound stops. Conclusion: vibration makes sound, and when vibration stops the sound stops too.
- Step 2: Find the sources of vibration around youNotice where everyday sounds come from: hold your hand near a radio speaker while it plays and you feel the air trembling; wind makes wires vibrate with a moaning sound; a door panel vibrates when knocked; piano strings vibrate when played; and when we talk or sing, the vocal cords in our throat vibrate. Search for more: what else vibrates while making sound at home? Remember how to observe: watch with your eyes whether something shakes, touch gently to feel the trembling, and listen for when the sound stops.
- Step 3: Bigger vibration, louder soundCompare on the drum: tap lightly and the sound is soft with the head barely trembling; strike hard and the sound is clearly louder, the head swings widely and the beans jump higher. Compare the two: small vibration, small sound; big vibration, big sound. Speaking is the same: shouting means big vibrations of the vocal cords, whispering means small ones. So loudness is decided by the size of the vibration — increase the vibration to be louder, reduce it to be softer. That is also why a radio volume knob can adjust the loudness.
- Step 4: Meet the echoOn a mountain or in a big hall, shout towards the distance and a moment later you hear yourself again — that is an echo: the sound travels forward, hits the cliff or wall and bounces back, like a ball rebounding. An echo needs enough distance to be heard clearly, so open spaces and big walls show it best. In a room the walls are too close; the echo returns at once and blends with the original sound, so we hardly notice. Bathroom tiles are hard and smooth and reflect plenty of sound, which is why singing there sounds extra bright.
- Step 5: Design your own sound experimentsTry designing experiments yourself. First, tap the same drum with three strengths — soft, medium and hard — and record how the loudness feels each time. Second, place beans on the drumhead and watch them jump higher the harder you strike, proving bigger vibration. Third, compare the echo of singing in a bedroom and in the bathroom. In your records, write clearly what you did, what you observed and what you concluded. Experiments let you see with your own eyes: vibration makes sound, and its size decides the loudness.
- Step 6: Protect our earsSounds that are too loud damage hearing: staying long in noisy places harms the tiny parts inside the ears, and hearing slowly gets worse — it cannot be restored. How to protect: cover your ears near construction sites or passing aircraft; keep earphone volume moderate — you should still hear someone talking beside you — and use them no more than an hour at a time; leave very noisy places quickly; tell an adult if your ears feel unwell. Hearing is precious: without birdsong or the teacher's voice, learning and life suffer greatly.
5Worked example Example
Example: Tim taps the big drum lightly first, then strikes it hard. What happens to the drumhead, and how do the two sounds differ? Why?
- Light tap: the drumhead vibrates slightly and the sound is soft.
- Hard strike: the drumhead vibrates widely — you can even see it shaking — and the sound is clearly loud.
- Compare: the two sounds have the same character but different loudness, because the vibrations differ in size.
- Check: put beans on the drumhead; the harder the strike, the higher the beans jump — bigger vibration means louder sound.
- Answer: Sound comes from vibration: the vibrating drumhead makes the drum sound. Struck hard, the head vibrates greatly and the sound is loud; tapped lightly, the vibration is small and the sound soft. Beans jumping on the drumhead are the evidence of vibration.
6Common mistakes Mistakes
7Quick check Quick check
Q1How are sounds produced?
Q2The bigger the vibration, the ___ the sound.
Q3Whispering — are the vocal cords vibrating much or little?
Q4What is an echo?
Q5Give one example of a vibrating object making sound.
8Recap Recap
- Vibrating objects make sounds.
- When vibration stops, the sound stops.
- The bigger the vibration, the louder the sound.
- Sound bouncing off walls forms echoes.
- Very loud sounds damage hearing — protect your ears.