🔊 How Do Computers Store Sound?

Analogue vs Digital Converter

Sound is a continuous wave — but computers only understand 1s and 0s. See how sampling turns a smooth wave into digital data, and why quality depends on how often you sample.

CS GCSE §1.2 DigiTech GCSE §1.1.1

🤔 What's the difference between analogue and digital?

Analogue = continuous, smooth — like a real sound wave or a vinyl record. Infinite detail.

Digital = discrete, stepped — like a staircase. Stored as numbers (samples) at fixed intervals.

📸 Analogy: Imagine drawing a smooth curve, then trying to recreate it using only LEGO bricks. More bricks (higher sample rate) and thinner bricks (higher bit depth) = closer to the original.

🎛️

Controls

Sample Rate: 20 samples

How often we measure the wave (more = better quality, bigger file)

Bit Depth: 4 bits (16 levels)

Precision of each measurement (more bits = more accurate, bigger file)

🔵 Blue = original analogue wave 🟢 Green dots = digital samples 🟩 Green line = reconstructed digital version

📊

File Size Calculator

📖

Key Terms

Sample Rate	How many times per second we measure the wave. Measured in Hz. CD quality = 44,100 Hz (44,100 samples every second!)
Bit Depth	How many bits used to store each sample. More bits = more precise. CD = 16 bits = 65,536 possible levels
File Size	= sample rate × bit depth × duration × channels. This is uncompressed — MP3 compression makes it much smaller
Nyquist Theorem	You need to sample at at least double the highest frequency in the sound. Humans hear up to ~20kHz, so CDs sample at 44.1kHz (just over double)