Audio Representation
1 · Analogue Sound Wave
Higher frequency = higher pitch (Hz = cycles per second)
Height of the wave: determines how loud the sound is
Wave frozen: adjust sliders to explore
Key terms
Frequency: cycles per second (Hz); determines pitch
Amplitude: height of the wave; determines volume
Wavelength: distance of one complete cycle
Continuous analogue wave: this is how sound exists in the real world
2 · Digital Sampling
Bit Depth (sample resolution)
Number of bits used per sample, determines how many quantisation levels exist
Sample Rate
How many samples taken per second, higher rate captures more detail
Length of the recording in seconds (for file size calculation)
Key terms
Sample rate: samples taken per second
Bit depth: bits used per sample (= quantisation levels = 2ⁿ)
Quantisation: rounding each sample to the nearest level
Blue = original analogue wave · Orange = digital approximation (sampled & quantised)
3 · File Size Calculation
File Size Calculation (mono, uncompressed)
File size (bits) = Sample rate × Bit depth × Duration
File size (bytes) = File size (bits) ÷ 8