Digital Sound

Digitizing analogue sound waves using Sampling.

Think of it like: The Flipbook

Sound is a continuous wave, but computers can only store "snapshots". Think of a stick-man animation in the corner of a notebook.

  • Sample Rate: How fast you flip the pages (Frames per second). Faster flipping = smoother movement.
  • Bit Depth: How detailed your drawing is on each page. stick man (low) vs Mona Lisa (high).

Theory

Time (s) →

Analogue to Digital: Sound is captured by a microphone (Analogue) and converted to binary (Digital) by sampling.

Sample Rate (Hz): How many times per second the sound is measured. Higher = better quality.

Bit Depth: Number of bits per sample. Determines accuracy of the wave height.

File Size = Sample Rate x Duration x Bit Depth

See the Details

Use the Audio Grapher to visualise exact sample points and bit depth.

Launch Audio Grapher

Check Your Understanding

1. What is the definition of Sample Rate?

2. If you increase the Bit Depth of a sound file, what happens?

3. Why must sound be digitised to be stored on a computer?

Numerical Exam Scenario (AO2)

1 / 3

The Examiner's Eye

Banned Practices Warning! In your exams, NEVER use the terms "Bit Rate" or "Sampling Frequency". These are outdated or A-Level terms that will often lose you marks. You must use the exact OCR specification terminology: Sample Rate and Bit Depth.

"A podcaster records a 10-second vocal intro. The recording software uses a Sample Rate of 2000 Hertz and a Bit Depth of 8-bits. Calculate the uncompressed file size of this recording in Kilobytes (KB)." (3 marks)