- Define and explain How Sounds Are Made in your own words
- Use key terms such as vibration accurately
- Apply what you have learned to new examples and questions
- Avoid the common mistakes learners make with this topic
Every sound you have ever heard began as a vibration. Those vibrations journey through air, water or solid ground until they reach your ears. This chapter follows sound from its source to your brain.
This lesson focuses on How Sounds Are Made: linking every sound you hear to a vibrating object.
Linking every sound you hear to a vibrating object.
Key ideas
Sounds are made by vibrations
Pluck a guitar string and it vibrates, pushing the air back and forth — that is what your ear detects as sound. The vibrating object can be a string, a drum skin, vocal cords or a loudspeaker cone. No vibration, no sound — it really is that simple.
Pitch depends on frequency, loudness on amplitude
Fast vibrations give a high frequency and a high-pitched note; slow vibrations give a low pitch. Big vibrations (large amplitude) make loud sounds, small ones make quiet sounds. Human hearing spans roughly 20 Hz to 20,000 Hz, and it fades at the top end as we age.
Key term — vibration: A rapid back-and-forth movement — the source of every sound.
You clap and hear the echo 2 s later. The speed of sound in air is 343 m/s. How far away is the cliff?
The sound travels to the cliff and back, so the 2 s covers twice the distance. Total distance travelled = speed × time = 343 × 2 = 686 m. Divide by 2 for the one-way distance: 686 ÷ 2 = 343.
Answer: 343 m away.
- Thinking sound travels in space Sound needs a medium — with no particles in a vacuum, astronauts must use radios.
- Mixing up pitch and loudness Pitch comes from frequency (how fast the vibration is); loudness comes from amplitude (how big it is).
Practice
The drum skin (membrane) vibrates and pushes the air back and forth.
Steel is faster: about 5000 m/s in steel versus about 343 m/s in air.
The pitch — hertz measures frequency, which determines pitch.
Space is a vacuum with no particles, so sound cannot travel between them — they use radios instead.
Quick check
Which of these best defines "vibration"?
Tightening a guitar string raises the note. Why?
A ship's sonar echo returns after 4 s. The speed of sound in water is 1500 m/s. How deep is the water?
- How Sounds Are Made: linking every sound you hear to a vibrating object.
- Sounds are made by vibrations: Pluck a guitar string and it vibrates, pushing the air back and forth — that is what your ear detects as sound.
- amplitude: The size of a vibration; a bigger amplitude means a louder sound.
- Watch out for: thinking sound travels in space