What's covered
Key facts
Sample Rate and Bit Depth
Bit depth is the number of bits used per audio sample.
Sampling — Sound to Numbers
The device that converts a sound wave into digital numbers is called an ADC (analog-to-digital converter).
Sample Rate and Bit Depth
Doubling the sample rate doubles the file size in bits (everything else equal).
Sampling — Sound to Numbers
CD audio is sampled at about 44 kHz (44,100 samples per second).
Sample Rate and Bit Depth
Higher bit depth means each sample stores finer detail of the sound's amplitude.
Sampling — Sound to Numbers
Sampling makes sound approximate because the continuous wave is reduced to a series of discrete points.
Sample Rate and Bit Depth
Higher sample rates AND higher bit depths both produce better-sounding audio, at the cost of a bigger file.
Sampling — Sound to Numbers
A higher sample rate gives a more accurate digital copy of the original sound, but a bigger file.
Sample Rate and Bit Depth
The standard unit for sample rate is the Hertz (Hz) — samples per second.
Sampling — Sound to Numbers
The sample rate is the number of samples taken per second.
Sample questions
A taste of the 19 questions in this topic, answers marked. Sign up to practise the full set with spaced repetition.
What does sample bit depth measure?
- ✓Bits used per sample
- •Frequency range the recording captures
- •Number of samples taken per second
- •Total file size of the audio recording
What does the sample rate measure?
- •Bit depth of each sample
- •Length of the recorded clip
- •Loudness of the recorded sound
- ✓Samples taken per second
What does higher bit depth mean for sound?
- ✓Finer detail in each sample
- •Quieter sound when played back
- •Shorter recording time on disk
- •Slower playback speed for files
Why does sampling create approximate sound?
- ✓Continuous wave becomes discrete points
- •Continuous wave becomes longer always
- •Continuous wave becomes louder always
- •Continuous wave becomes shorter always
What is the formula for sound file size in bits?
- •Resolution times depth squared
- •Sample rate minus depth times duration
- •Sample rate plus depth plus duration
- ✓Sample rate times depth times duration
Higher sample rate gives what?
- •Less accurate sound, smaller file
- ✓More accurate sound, bigger file
- •Same accuracy with a smaller file
- •Same sound, smaller file
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