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Art and culture · Music and sound

What is sound? Vibration, frequency and amplitude

When a guitar string vibrates, what actually reaches your ear? See and hear that sound is a vibration wave, that frequency makes a sound higher and that amplitude makes it louder.

  • 15 min
  • 2 simulations
  • Mini quiz

Updated:

Preview

The question

Pluck the thickest string on a guitar and you hear a deep, full sound. Pluck the thinnest and you hear a high, bright one. Both are played on the same guitar, with the same finger. So what exactly is the difference between the two sounds that reach your ear? And how does the sound travel metres away when the string isn't touching anything?

Try it yourself

No account needed: change the values and check your answer. Some simulations ask for a prediction before they start; it doesn't matter whether it's right or wrong.

Sound lab

A wave three times as dense

Change the frequency of the second tone with the slider or the plus and minus buttons. Compare how closely packed the waves are. If you like, press Play to hear the sounds; with the sound off, the waves and numbers are enough. Then press Check.

Prediction

Predict first

You want a string to make a higher sound. How should the string vibrate?

It doesn’t matter whether you’re right; the simulation opens once you choose.

Ordering

Sounds from low to high

Order the cards by dragging them or moving them with the keyboard, then press Check.

Prediction

Predict first

Which do you think is higher: a child's speaking voice or the orchestra's tuning note A (440 Hz)?

It doesn’t matter whether you’re right; the simulation opens once you choose.

Share: Share to Google Classroom (opens in a new tab)

Embed the simulation on your site

Paste this code into the HTML of your blog or school site. Visitors try the simulation without an account; no progress is saved.

The embedded page sets no cookies and does no tracking. A small link back to Kuazara sits underneath.

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Frequently asked

5 questions

Does "turning a sound up" make it louder or higher?

In everyday speech, "turning up" a sound usually means making it louder. In music, though, a "high pitch" means a high, bright sound. Loudness depends on amplitude and pitch on frequency; they are separate things. A low drum can be very loud and a high bell very quiet.

Does sound carry air from the source to your ear?

No. Air particles do not travel all the way to your ear; they swing back and forth in place and pass the push on to their neighbours. What travels is the vibration itself, like a "wave" in a stadium: everyone stays in place but the wave moves on.

Why can't you hear sound in space?

Sound travels by passing a vibration from one particle to the next. In the vacuum of space there are no particles to carry it, so even an explosion is completely silent. Astronauts talk by radio, using radio waves, which do travel through a vacuum.

What is the difference between frequency and amplitude?

Frequency is how many times per second the source vibrates (in hertz), and it sets the pitch: the higher the frequency, the higher the sound. Amplitude is how wide the vibration is, and it sets how loud the sound is. They are independent; you can sing a high note softly or a low note loudly.

When a violin and a flute play the same note, how can we tell them apart?

Real instruments do not produce a single frequency. Alongside the fundamental frequency, overtones at 2, 3, 4 times that frequency also vibrate. The mix of these overtones is different for each instrument and gives it its own timbre.