IGCSE 0625 / Section 3.4 / Core

Taller, or tighter.

Turn up the volume and the trace on an oscilloscope grows taller. Sing a higher note and the waves pack closer together. Two separate dials, amplitude and frequency, control two separate things you hear.

The key idea

The loudness of a sound depends on the amplitude of the wave: a larger amplitude is louder. The pitch depends on the frequency: a higher frequency is a higher pitch. The two are independent, so a sound can be loud and low, or quiet and high.

Definition · learn the exact words

The loudness of a sound is set by the amplitude of the wave, and the pitch is set by the frequency. A larger amplitude sounds louder; a higher frequency sounds higher in pitch.

larger amplitude → louder · higher frequency → higher pitch

On an oscilloscope a louder sound gives a taller trace, and a higher pitch gives waves that are packed more closely.

Section 01

Match the trace.

Adjust amplitude and frequency to match a target wave, and watch how each control changes a different feature.

Stage 1 · Learn

Check loudness and pitch

Four quick checks. Each correct answer earns XP and lights this skill on your star map.

Quick check+10 XP

The loudness of a sound depends on its...

Quick check+10 XP

The pitch of a sound depends on its...

Quick check+10 XP

A higher pitched note has a...

Quick check+10 XP

On an oscilloscope a louder sound shows up as a trace that is...

Section 02

Two dials, two effects.

Amplitude and frequency act independently, so changing one does not change the other.

Change you makeEffect on the sound
Increase the amplitudeLouder, the trace gets taller
Decrease the amplitudeQuieter, the trace gets shorter
Increase the frequencyHigher pitch, more waves in the same width
Decrease the frequencyLower pitch, fewer waves in the same width
Examiner trap

Amplitude controls loudness and frequency controls pitch, and they are independent. Turning up the volume makes the trace taller, it does not pack the waves closer. Packing more waves into the same width raises the pitch, it does not make the sound louder.

Stage 2 · Exam

Exam-style questions

Unlocks once the four checks above are done. Worth more XP, written in the style of Paper 2.

Finish the four checks above to unlock the exam questions
Exam style+20 XP

Two notes are shown on a CRO. Note X has a taller trace than note Y, but both have the same number of waves across the screen. Compared with Y, note X is...

Exam style+20 XP

A singer raises the pitch of a note without changing how loud it is. On a CRO the trace would show...

Exam style+20 XP

Which change makes a sound louder without altering its pitch?

Skill unlocked

Loudness and pitch, mastered.

Loudness and pitch are sorted. Keep the chain going.

-Rank -Level -Score -Topics
Go deeper · practice
Six original Cambridge-style questions
Amplitude as loudness, frequency as pitch, and reading both off an oscilloscope trace. Attempt each, then reveal the worked solution.
Stage 3 · master the unit
Waves challenge
Mixed questions across the whole unit, each one worth XP. Start this only when you feel confident across every topic in the unit, not just loudness and pitch.
Start the unit challenge →