3.3 Data RepresentationKey Facts

Sound File Size Calculation

Part of Images & Sound · GCSE GCSE Computer Science revision

This key facts covers Sound File Size Calculation within Images & Sound for GCSE Computer Science. Revise Images & Sound in 3.3 Data Representation for GCSE Computer Science with 18 exam-style questions and 16 flashcards. This topic shows up very often in GCSE exams, so students should be able to explain it clearly, not just recognise the term. It is section 8 of 12 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 8 of 12

Practice

18 questions

Recall

16 flashcards

Sound File Size Calculation

Formula:

  File Size (bits) = Sample Rate × Bit Depth × Duration × Channels
  File Size (bytes) = (Sample Rate × Bit Depth × Duration × Channels) ÷ 8

Example 1: CD Quality, 1 Second

  Sample Rate: 44,100 Hz
  Bit Depth: 16 bits
  Duration: 1 second
  Channels: 2 (stereo)
  
  File Size = 44,100 × 16 × 1 × 2
            = 1,411,200 bits
            = 1,411,200 ÷ 8
            = 176,400 bytes
            ≈ 172 KB per second
  
  For 3-minute song: 172 KB × 180 seconds = 30,960 KB ≈ 30 MB

Example 2: Telephone Quality, 10 Seconds

  Sample Rate: 8,000 Hz
  Bit Depth: 8 bits
  Duration: 10 seconds
  Channels: 1 (mono)
  
  File Size = 8,000 × 8 × 10 × 1
            = 640,000 bits
            = 640,000 ÷ 8
            = 80,000 bytes
            = 80 KB

Example 3: Comparing Quality Levels

  Same 1-second recording at different qualities:
  
  Telephone (8kHz, 8-bit, mono):
  8,000 × 8 × 1 × 1 ÷ 8 = 8,000 bytes = 8 KB/sec
  
  CD Quality (44.1kHz, 16-bit, stereo):
  44,100 × 16 × 1 × 2 ÷ 8 = 176,400 bytes = 172 KB/sec
  
  CD is 21.5× larger than telephone!

Keep building this topic

Read this section alongside the surrounding pages in Images & Sound. That gives you the full topic sequence instead of a single isolated revision point.

Sound Representation - Digital Audio Real-World Example: Why Music Files Are Big The Digital Camera Trick Image and Sound Data Representation

Practice Questions for Images & Sound

What does colour depth refer to in a digital image?

A. The number of pixels in the image
B. The number of bits used to represent each pixel's colour
C. The physical dimensions of the image in centimetres
D. The number of samples taken per second

1 markfoundation

Explain the effect of increasing colour depth on a digital image. Refer to both file size and image quality in your answer.

3 marksstandard

Quick Recall Flashcards

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Sound Representation - Digital Audio

Real-World Example: Why Music Files Are Big