1. DATA REPRESENTATION: SOUNDS GCSE Computing

2. Learning Objective ■ To understand how sounds are represented in Binary ■ To be able to convert a sound wave into a binary form. ■ Success Criteria ■ To be able to explain what “analogue” is ■ To be able to explain what is meant by “sampling” ■ To be able to encode a simple sound wave

3. Sound Waves ■ Remember from lesson 1: ■ This is a sound wave, it has been detected using a microphone. ■ The microphone changes the amount of electricity to produce this Sound Wave ■ It is analogue, which means continually changing

4. Converting to Digital 1.The analogue sound is received by a microphone 2.This is converted into an electrical analogue signal 3.The signal amplitude (height of wave) is measured at regular intervals (sampling) 4.These levels are rounded off (quantisation) 5.The values of these are stored as a series of binary numbers in a file.

5. Example: ■ Sound Wave

6. Example: Sample Amplitude

7. Example: ■ Finally, each amplitude would have to be converted to a binary number. ■ We haven’t covered numbers which are not whole numbers (integers) yet… ■ Info: Numbers with a fractional part, such as 5.6, 0.0003 etc are called Real Numbers in computing Sample Amplitude

8. Playing the sound ■ The digital sound file is used to play back the sound. ■ The sound wave is reconstructed from the samples. ■ The sound is higher quality if: – There are more samples – The sound is sampled more accurately ■ The sound is lower quality if: – There are less samples – The sound is sampled less accurately