LESSON OUTCOME I understand and can explain how sound is stored
by a computer system.
Slide 6
WHAT DO I NEED TO KNOW AT GCSE? (a)Explain how sound can be
sampled and stored in a digital form (b)Explain how sampling
intervals and other considerations affect the size of a sound file
and the quality of its playback I understand how sound is stored by
a computer system.
Slide 7
THEORY NOTES Sound just like images are stored in binary format
that is then read and interpreted by a computer with the use of
metadata. Sound is often a continuously varying data (analogue) but
a computer needs this in binary format so it needs to be
transferred from analogue to digital form. To do this we sample the
sound wave at set intervals and record the values, this set of
values is saved and replayed by the computer. I understand how
sound is stored by a computer system.
SO WHAT'S THE DIFFERENCE? Uptown Funk at Normal 96000hrtz
sampling and bit rates. Uptown Funk at Half 48000hrtz sampling and
bit rates. Uptown Funk at Quarter 24000hrtz sampling and bit rates.
I understand how sound is stored by a computer system.
Slide 10
TASK Add a description to your graphs about what we have just
discussed. You can use the notes below to help you; The sample rate
affects the quality of the sound, a high or more frequent sample
rate improves quality as it is closer to the original but involves
a larger file size. A lower sample rate will have reduced quality
as it is less close to the original however the trade off is a
lower file size.
Slide 11
BIT RATE The bit rate is the amount of data that can be used to
store each sample. So as before a higher bit rate will lead to
better quality playback but will require a large file size, a lower
bit rate will reduce the file size but result in lower quality
playback. I understand how sound is stored by a computer
system.
Slide 12
IMPORTANT KEYWORDS Dont confuse sample rate and bit rate! They
are different. The sample rate is how frequently the data is
sampled. The bit rate is the amount of data stored at each sample
point. I understand how sound is stored by a computer system.
Slide 13
QUESTIONS How does the sample rate affect the quality of the
playback for an MP3 sound track? What factors affect the file size
for a sampled MP3 track? Why are there so few tracks on a typical
audio CD? Which sound file formats (MP3, WAV etc.) sample most
frequently and less frequently? I understand how sound is stored by
a computer system.