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2.4 Digital Analogue
Topic 2.4 — Digital and Analogue

Sampling Playground

Explore how digital audio captures analogue sound. Play with sample rate, bit depth, and file sizes — then put it all together.

Sample Rate Explorer

How Sampling Captures Sound

Adjust the sample rate and wave frequency to see how digital sampling captures an analogue signal. Watch what happens when you drop below the Nyquist threshold.

Samples per cycle
6
Nyquist minimum
4 per cycle
Status
Good capture
24 samples
464
2× base
LowHigh
Show reconstructed signal
Analogue signal
Sample points
Reconstructed digital
Nyquist threshold
Bit Depth Explorer

Quantisation Staircase

Drag the slider to see how bit depth shapes the staircase approximation of an analogue signal. The shaded area shows quantisation error.

Analogue signal
Quantised (digital)
Quantisation error
4-bit
2-bit (coarse)16-bit (CD quality)
Amplitude levels
2^4
16
Dynamic range
4 × 6
24 dB

More bits = more levels = quieter noise floor. Each additional bit roughly doubles the number of amplitude levels, adding ~6 dB of dynamic range and reducing the quantisation noise that fills the error-shaded area above.

File Size Challenge

Estimate the File Size

Type your estimate in MB before revealing the answer. Commit first — no hints.

1/5
Formula: Sample Rate × (Bit Depth ÷ 8) × Channels × Duration ÷ 1,048,576 = MB
Scenario 1

3-minute stereo podcast at 16-bit / 44.1 kHz

Sample rate
44.1 kHz
Bit depth
16-bit
Channels
Stereo
Duration
3 minutes
AO3 / AO4 — Your Turn

Extended Response Practice

Apply what you've explored. Write a short response to the scenario below.

Scenario

A client asks you to record a podcast for streaming distribution. They want the best quality possible but are concerned about file sizes for hosting. Describe the sample rate and bit depth you would recommend, and evaluate why these settings are appropriate for this context.

How to answer well
AO3 — DESCRIBE

Identify the technical detail → explain what it does

AO4 — EVALUATE

Why is this the right choice? What are the trade-offs?

IDENTIFY → EXPLAIN → EVALUATE
Your Response

0 characters

Self-Check — tick after writing
I identified specific sample rate and bit depth values
I explained what these settings control (frequency range / dynamic range)
I evaluated WHY these are appropriate for podcasts specifically
I considered the trade-off between quality and file size
I used correct technical vocabulary (e.g., Nyquist, quantisation, dynamic range)

Tick at least 3 items to unlock the model answer

A-Level Music Technology — Component 4: Producing and Analysing

What you learned

  • Visualise how sample rate affects the accuracy of digital audio capture
  • Understand aliasing and the Nyquist theorem through interactive exploration
  • See how bit depth determines quantisation accuracy and dynamic range
  • Calculate uncompressed audio file sizes from sample rate, bit depth, channels, and duration
  • Apply digital audio knowledge in an AO3/AO4 extended response
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