Sampling Sound into Numbers
Recording sound by measuring the wave thousands of times a second and storing each measurement as a binary number. Sample rate and bit depth change the quality and the size together.
What a learner can do afterwards
- Explain what a sample is and what the sample rate counts
- Say what a higher sample rate or bit depth does to quality and to file size
- Explain why a digital recording can never hold the whole wave
1 · Read
Sound in the air is a smooth wave of pushes and pulls that never stops changing. A computer cannot store a smooth curve, so it measures the height of the wave at many tiny steps, much like a picture stores many tiny pixels. Each stored measurement is called a sample, and playing the numbers back fast lets your ear hear the wave again.
CD-quality music measures the wave 44,100 times a second for each channel, and that count is its sample rate. More samples per second means the copy follows the original more closely. A lower rate keeps less detail, so the copy drifts further from the real wave.
Each sample is stored with a fixed number of bits, called the bit depth. More bits give finer steps between quiet and loud. Bitrate counts the bits of audio stored each second. A higher sample rate or a higher bit depth keeps more detail, and both make a bigger file, just as more pixels or more colour depth make a bigger image.
Remember the gap: the wave is continuous, but samples are finite steps. A digital recording can never hold the whole wave, only close snapshots of it.
Samples freeze a smooth wave as numbers, and more of them means better sound in a bigger file.
Lesson text, flashcards and practice questions with worked steps, written for this dataset.
Two readings adapted from the academy articles Converting analog data to binary and Sound is a longitudinal wave. One reading was written for this dataset. Two videos are linked from the academy collection.
2 · Watch
En anglaisTake it off screen
Where it sits
Optional connections
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.