Representing Sound
Overview
Sound is a wave in the air. It never stops changing, it has no edges, and between any two instants there is another instant. A computer has none of those qualities: it stores a finite list of whole numbers and nothing else. So recording sound is not a matter of copying it into a machine. It is a matter of measuring it, over and over, fast enough that the list of measurements can be turned back into something a human ear accepts as the original.
This lesson explains what that measuring process is, what the two settings that control it actually do, and how to calculate the size of the file that results. You will learn why a recording made at a higher sampling rate sounds better and costs more, what a sample resolution of 8 bits gets you that 4 bits does not, and how to run the file size formula backwards to find a missing setting.
Objectives
- Understand that sound is analogue and that it must be converted to a digital form for storage and processing in a computer. Understand that sound waves are sampled to create the digital version of sound. Describe the digital representation of sound in terms of:
- sampling rate
- sample resolution.
- Calculate sound file sizes based on the sampling rate and the sample resolution.
Mind map
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Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Representing Sound. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- What does a single sample of a sound record? A. The amplitude of the wave at a point in time B. The number of bits in the file C. The length of the recording D. The number of samples taken per second Answer: A
- A recording has a sampling rate of 16,000 Hz. What does this mean? A. Each sample uses 16,000 bits B. 16,000 samples are taken every second C. The recording lasts 16,000 seconds D. The file is 16,000 bytes Answer: B
- A 4 second recording uses a sampling rate of 10,000 Hz and a sample resolution of 8 bits. What is the file size in bits? A. 40,000 B. 80,000 C. 320,000 D. 640,000 Answer: C
- A sample resolution of 8 bits allows how many different amplitude levels? A. 8 B. 16 C. 64 D. 256 Answer: D
- A recording is remade with the sampling rate doubled and everything else unchanged. What happens to the file size? A. It halves B. It stays the same C. It doubles D. It quadruples Answer: C
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