Sound, Pitch and Volume

Section: Physics | Syllabus: Cambridge Primary Stage 5 Science (0097)

Sounds Come from Vibrations

A vibration is a repeated back-and-forth movement.
Sounds are made by vibrating sources such as strings, drum skins, rulers, speakers and vocal cords.
The vibrating source makes the particles of the surrounding material - usually air - vibrate too, and this vibration carries the sound to the ear.

Pitch and volume are two separate properties of a sound, and each is linked to a different feature of the vibration.

A faster vibration gives a higher pitch; a bigger vibration gives a louder sound

Sound property	Words used	Linked vibration
Pitch	High or low	Faster vibration gives higher pitch; slower gives lower pitch
Volume	Loud or quiet	Bigger vibration gives louder sound; smaller gives quieter sound

Plucking or hitting a source with more force increases the volume of the sound.
A shorter, tighter or thinner string usually gives a higher pitch.
A longer, looser or thicker string usually gives a lower pitch.
Change only one factor at a time when investigating sound, so that the effect of that one change can be seen clearly.

Worked Example: Changing a String

Question: A learner shortens a vibrating string and plucks it with more force. Describe the changes in pitch and volume. [2]

Shortening the string makes it vibrate faster, so pitch increases. Plucking harder creates a bigger vibration, so volume increases. Answer

The sound has a higher pitch and a louder volume.

MistakeHigh pitch means loud.

FixPitch is high or low; volume is loud or quiet. They describe different properties of a sound.

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