Do it now activity Last lesson we learnt about how images are stored on a computer. Can a computer decide what colours to use in an image? How does a computer know what colours to use?

Learning objectives Recognise how sound is represented in a computer system Investigate how computers use metadata to re-create sound Investigate how an increased sample rate could affect efficiency

Learning outcomes By the end of this lesson you will be able to .... ALL (C) Explain how sound is represented on a computer using binary MOST (B) Explain how a computer would use metadata to re-create an image SOME (A) Explain what effect sample rate has on file size and sound quality

Find a picture to represent sound on the eardrum Recognise how sound is represented in a computer system Investigate how computers use metadata to re-create sound Investigate how an increased sample rate could affect efficiency Learning objectives New Learning What is sound? Find a picture to represent sound on the eardrum What is sound? Find a picture to represent sound on the eardrum. Print off and stick in books Amplitude Frequency Megahertz Sound Analogue Digitising Sampling Pitch Binary

Amplitude and Frequency Recognise how sound is represented in a computer system Investigate how computers use metadata to re-create sound Investigate how an increased sample rate could affect efficiency Learning objectives New Learning Amplitude and Frequency Work through several combinations Amplitude Frequency Megahertz Sound Analogue Digitising Sampling Pitch Binary

New Learning Amplitude is how loud the sound is Amplitude Frequency Recognise how sound is represented in a computer system Investigate how computers use metadata to re-create sound Investigate how an increased sample rate could affect efficiency Learning objectives New Learning Amplitude is how loud the sound is Copy into books Amplitude Frequency Megahertz Sound Analogue Digitising Sampling Pitch Binary

New Learning Frequency is how often the sound is measured Recognise how sound is represented in a computer system Investigate how computers use metadata to re-create sound Investigate how an increased sample rate could effect efficiency Learning objectives New Learning Frequency is how often the sound is measured This is measured in Hertz (Hz for short) Frequency is also called pitch Copy into books Amplitude Frequency Megahertz Sound Analogue Digitising Sampling Pitch Binary

New Learning Amplitude Frequency Megahertz Sound Analogue Digitising Recognise how sound is represented in a computer system Investigate how computers use metadata to re-create sound Investigate how an increased sample rate could effect efficiency Learning objectives New Learning A frequency of 1 Hz means one wave cycle per second. A frequency of 10 Hz means ten wave cycles per second, where the cycles are much shorter and closer together. Audacity uses 44.1Khz. Even this is not good enough for the music industry. They use 44Khz Amplitude Frequency Megahertz Sound Analogue Digitising Sampling Pitch Binary

Talk Task On your whiteboards Is the sound quiet or loud? Recognise how sound is represented in a computer system Investigate how computers use metadata to re-create sound Investigate how an increased sample rate could effect efficiency Learning objectives Talk Task On your whiteboards Is the sound quiet or loud? Is the sound low or high pitched? Use audacity to record the following 2 sentences In a quiet, squeaky voice (you are a mouse called “Amp”) ; say “Amplitude is how loud the sound is, Squeak!” In a loud deep voice, (you are an army sergeant called “Mega Hurts”) say; “Frequency is measured in megahertz, Hoo-hah!” Zoom in on the sound wave until you can see a clear line then play the sound for the mouse. And Sergeant. Students should answer the questions on their white boards AMP – low amplitude, high frequency Sergent – high amplitude, low frequency Amplitude Frequency Megahertz Sound Analogue Digitising Sampling Pitch Binary

Computers use sampling to re-create sounds Recognise how sound is represented in a computer system Investigate how computers use metadata to re-create sound Investigate how an increased sample rate could effect efficiency Learning objectives Independent Task 1   2 0.5 3 4 -0.5 5 -1.5 6 -1 7 8 Computers use sampling to re-create sounds So how does the computer know what the sound sounds like? Join the dots…you need to draw your own dots though! Here they are: On the X axis, put a dot at the following co ordinates. Have a go at drawing the sound wave You have just done what the computer does to reassemble an audio file.   To record a sound, the computer SAMPLES (aka, measures) the sound at regular points, (frequency). Then it converts the sample measurements into binary code. Amplitude Frequency Megahertz Sound Analogue Digitising Sampling Pitch Binary

Learning Development Amplitude Frequency Megahertz Recognise how sound is represented in a computer system Investigate how computers use metadata to re-create sound Investigate how an increased sample rate could effect efficiency Learning objectives Learning Development The higher the sampling rate the smoother the curve. Demonstrate this by opening an MP3 file in audacity, click on Effect > change tempo and decrease tempo without altering pitch – you can now hear the sampling What does a computer use to break up a sound into smaller chunks? Answer on whiteboards - sampling What are these samples converted into? Answer on whiteboards - Binary How does the computer know that the binary should be treated as a sound file rather than an image file? Answer on whiteboards - Metadata Amplitude Frequency Megahertz Sound Analogue Digitising Sampling Pitch Binary

Independent Task Access on Weebly Term 3 - Lesson 4 Recognise how sound is represented in a computer system Investigate how computers use metadata to re-create sound Investigate how an increased sample rate could effect efficiency Learning objectives Independent Task Access on Weebly Term 3 - Lesson 4 Complete the independent task based on the level you are working towards Amplitude Frequency Megahertz Sound Analogue Digitising Sampling Pitch Binary

Plenary How is sampling a sound the same as digitising an image? Recognise how sound is represented in a computer system Investigate how computers use metadata to re-create sound Investigate how an increased sample rate could effect efficiency Learning objectives Plenary How is sampling a sound the same as digitising an image? Amplitude Frequency Megahertz Sound Analogue Digitising Sampling Pitch Binary

Learning outcomes By the end of this lesson you will be able to .... ALL (C) Explain how sound is represented on a computer using binary MOST (B) Explain how a computer would use metadata to re-create an image SOME (A) Explain what effect sample rate has on file size and sound quality