Calculation of sound file sizes
Lesson details
Learning outcome
I can explain how sample bit depth and sample rate affect the size and quality of a sound file.
Key learning points
- Adjusting the sample bit depth when digitising sound affects the accuracy of the sound being captured.
- Adjusting the sample rate when digitising sound affects the completeness of the sound being captured.
- The file size of a sound file is determined from its sample bit depth, sample rate and duration.
- Selection of sample bit depth and rate depend on the use of the sound and the limitations imposed by the file size.
Keywords
Accuracy - how close a measurement is to its actual value
Duration - the length of time that something lasts
Common misconception
Any sound that is digitised is going to be noticeably different to the original sound.
When sound is turned into digital form with a high enough sampling rate and sample bit depth, the difference from the original sound is too small for human ears to notice.
Teacher tip
There are lots of examples of websites that provide audio of changable qualities. Find some music that pupils recognise and compare the difference in the quality to understand the effect sample rate and bit depth have on the perceived quality of audio.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.What is a sound sample?
Q2.What does digitisation mean?
Q3.What does bit depth in sound sampling refer to?
Q4.Put these steps in the correct order to digitise sound:
Q5.What is the term used to describe the number of bits used to represent a sound sample?
Q6.Match the terms with their definitions:
a measure of a sound wave at a point in time
converting data into a binary sequence
the number of bits used to represent a sample
Assessment exit quiz
6 Questions
Q1.What does adjusting the sample bit depth affect when digitising sound?
Q2.What three factors determine the size of a sound file?
Q3.What happens if the sample rate is too low?
Q4.What is the effect of increasing both sample rate and sample bit depth?
Q5.Calculate the file size in kB of a 2-minute sound recording that has a sample rate of 2000 Hz and a sample bit depth of 6 bits.
Q6.Calculate the file size in kB of a 3-minute sound recording that has a sample rate of 1000 Hz and a sample bit depth of 2 bits.
To help you plan your 10 computer science lesson on: Calculation of sound file sizes, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 10 computer science lesson on: Calculation of sound file sizes, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 4 computer science lessons from the Representation of text, images and sound unit, dive into the full secondary computer science curriculum, or learn more about lesson planning.