Sound sampling, sample rate and bit depth

Overview

How sound is sampled, sample rate, bit depth and duration, their effect on quality and file size, the sound file size formula, and worked calculations.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   Why must sound be converted before a computer can store it?

   Model answer

   Sound is an analogue wave that varies continuously. A computer can only store digital data, so the sound must be converted into binary.

2. 2

   Describe how sound is sampled.

   Model answer

   The amplitude of the sound wave is measured at regular time intervals. Each measurement, called a sample, is stored as a binary number.

3. 3

   What is the sample rate of a recording?

   Model answer

   Sample rate is the number of samples taken each second. Sample rate is measured in hertz (Hz).

4. 4

   What does a sample rate of 44.1 kHz mean?

   Model answer

   A sample rate of 44.1 kHz means 44,100 samples are taken every second. CD-quality audio uses this sample rate.

5. 5

   What is bit depth?

   Model answer

   Bit depth is the number of bits used to store each sample. A common bit depth is 16 bits.

6. 6

   How many different amplitude values can a 16-bit sample store?

   Model answer

   A 16-bit sample can store 65,536 different values. The figure comes from 2¹⁶ = 65,536.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.