Sound Waves: See Pitch and Loudness
Understand that sound is a pressure wave made by a vibrating object, that frequency (in hertz) decides the pitch, and that amplitude decides the loudness, with the two being independent.
Before you try
What if you made a sound higher without making it louder? Is that even possible?
Try it out
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What happened?
Move a control to see what changes and why.
The wave is drawn as one perfect shape in one place. Real sound spreads in every direction, echoes, and fades as it travels.
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Try these ideas
- Keep the amplitude fixed and raise the frequency. Does it get louder or higher?
- Compare the bass drum and whistle presets on the waveform graph.
- Press Match this sound and set a high, quiet tone.
Why it works
A speaker cone pushes the air in front of it, squeezing molecules together into a compression and then leaving a thinner gap called a rarefaction. That pattern travels outward at about 343 metres per second in air. How many times the cone vibrates each second is the frequency, measured in hertz, and that sets the pitch: more vibrations mean a higher note. How far the cone moves is the amplitude, which sets the loudness.
In this simulator you set the frequency and amplitude, choose a waveform and, if you want, play the real tone through your speakers. The wave picture, wavelength and period all update as you go. The vibration in the picture is slowed down so it stays visible, because a real cone at these frequencies moves far too fast to see.
Check your understanding
Question 1 of 4
You raise the frequency of a tone but leave the amplitude alone. What changes?
Which sound has the longer wavelength in air?
What is actually travelling away from a speaker?
A 262 Hz note takes how long for one complete vibration?
Explain it in your own words
What changed? Why did it happen? Where might you notice this in everyday life?
For parents & teachers
- Pluck a rubber band stretched tight, then loose, and listen to the pitch change.
- Ask why a big drum sounds lower than a small one.
- Discuss why sound cannot travel through empty space.