This document provides instructions for a lesson on data representation and audio compression. The lesson objectives are to understand why compression is used, explore the differences between 16-bit and 8-bit sound files, and complete workbook questions. Students will work with an audio sample, save it in both 8-bit and 16-bit formats, and compare the file sizes. They will also research the original song used in the sample for homework.

1. Data Representation
Lesson 9
1

2. Starter
You have all be given a keyword or description.
You are going to have to match up the keyword
and description.
So carefully work your way around the room and
try and find the match to your piece of paper.
2

3. Objective of the lesson
• To be able to compress audio files
• All of you will:
• to discover why compression Is used.
• Most of you will:
• explore the difference between 16 bit and 8 bit sound files.
• Some of you will:
• Complete the questions in your workbook.
3

4. • Today we are going to be working with an audio
sample.
• The homework is to find out who the created the
original song!
• Homework in for next lesson.
• Write in your planners!
4
Homework

5. Compression
• What is compression?
• Why do we think it is used?
• How do computers communicate with each other
over a network?
• Computer programs are transported in packets
over the network cables. Compression is a way to
reduce the bandwidth used and to reduce other
errors that may happen in the transportation.
5

6. Compression in real terms
• Jay Zee has created a new web service for
musicians. It’s a cloud based solution and this
link shows us the difference in compression.
• http://tidal.com/gb/video/lossless-explained
6

7. Analogue and Digital sound
7

8. Analogue and Digital
• You have all be given a sheet of an 8 bit binary
table
• Draw the Sine wave as shown in the previous
slide.
• Now colour in all the cells that the wave
passes
8

9. Audacity
• Open up the audacity program found in ICT
program list on your computer.
• A sample track is being passed around on a
USB stick. Save this to your work area and
open the track in the program.
9

10. Demonstration
• The teacher will demonstrate how to save the file
in an 8 bit format
• You will save the sample in a 16 bit format.
• In a folders view, find the samples you have just
saved and right click to view the properties.
• What are the file sizes? Write down the answer in
your books.
10

11. Plenary
• What is compression?
• Why do we need to use it?
• What is the difference between analogue and
digital signals?
11

12. • Find the original track name for the sample.
• Home work in for tomorrow
12
Homework