Sampling sound: analogue to digital

5 minAS Level1.2.6

AI-drafted, independently checked · not yet teacher-reviewed

By the end of this lesson

By the end you can explain how sound is sampled and encoded, using the terms analogue data, digital data, sampling, sampling rate and sampling resolution.

Computers can't store a wiggle

Sound is air pressure wobbling smoothly up and down. A computer can only store binary numbers.

So we cheat: we measure the wave over and over, very fast, and store the measurements. Done well enough, your ears can't tell.

Definition

Analogue data

Data that vary continuously and can take any value within a range, such as the changing air pressure of a sound wave.

Definition

Digital data

Data stored as discrete (separate, fixed) values, represented in binary.

From air to binary

A microphone turns the sound wave into an analogue electrical signal.
An analogue-to-digital converter (ADC) measures the amplitude (height) of the signal at regular time intervals. This is sampling.
Each measurement is rounded to the nearest value that the available bits can store, and saved as a binary number.
To play it back, a digital-to-analogue converter (DAC) turns the numbers back into a varying signal for the speaker.

Quick check

Fill in the blanksQuestion 1 · Recall

A microphone turns sound into an electrical signal. An measures the of the signal at regular time intervals and stores each measurement as a binary number.

Answer the question above to continue.

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