Cambridge International AS &

Topic support guide
Cambridge International AS & A Level
Information Technology
9626
For examination from 2017
Topic 10 Sound and video editing
Sub-topic 10a Sound editing – Task 1
Audio editing task guide 9626 Sub-topic 10a Sound editing – Task 1
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Version 1
Audio editing task guide
These tasks could be attempted using almost any audio editing application. There are also
a number of video editing applications with the facilities to edit audio to the extent required
for the tasks. The software used in the screenshots shown below was Audacity®.
Audacity was chosen because it is a free open source digital audio editor and recording
application and is available for different operating systems such as Windows, OS X and
Linux varieties. Audacity can record audio from multiple sources and can be used for postprocessing of all types of audio.
The tools needed for these tasks are simple and available in all audio editing applications. In
most cases the menu items and tool buttons use the same text and the same symbols.
These tasks are designed to be undertaken as a learning process. Learners should be
encouraged to use the tasks to explore the menu items and tools available in the software.
Often there is more than one way to satisfy the requirements of the task. At first, the
exercises should be about exploring a variety of options and not about determining the most
efficient methods. It is recommended therefore, that learners begin the tasks without access
to this tutorial material.
Task 1
(1) Extract five seconds of ticking clock sound from the Clock_tick.wav file. Export the file in
.mp3 format at 128 kbps.
The easiest way to open the Clock_tick.wav file is to drag and drop the file into the Audacity
window.
Audio editing task guide 9626 Sub-topic 10a Sound editing – Task 1
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From the timeline, you can now see the file is over seven seconds long.
Timeline
The most accurate way to set the length of the sound clip is to use these controls.

You can set the length of the clip to five seconds by using the
length control or by using the selection tool and dragging the play
head.
The ‘Trim Audio’ button cuts the clip down to five seconds.
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Audio editing task guide 9626 Sub-topic 10a Sound editing – Task 1
All that remains is to save the clip as an mp3 file.
Select MP3 files and
set the option to 128
kbps.
(2) Trim the Alarm_ring.wav file to be five seconds long. Export the file in .mp3 format at
128 kbps.
Drag and drop the Alarm_ring.wav file.
Audio editing task guide 9626 Sub-topic 10a Sound editing – Task 1
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Set the length and trim as before.
This time we need to only
export the selected audio track.
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Audio editing task guide 9626 Sub-topic 10a Sound editing – Task 1
(3) Create a single file of the clock ticks followed by the alarm ringing (10 seconds).
Export the file in .mp3 format and save as timer1.mp3.
Now we need to start the ‘Alarm_ring’ track at five seconds…
Use the time shift tool to move the ‘Alarm_ring’ clip to start at five seconds.
…and add the track to the end of the ‘Clock_tick’ track.
Drag and drop the ‘Alarm_ring’
waveform to the end of the
‘Clock_tick’ track.
Close the ‘Alarm_ring’.
track
Audio editing task guide 9626 Sub-topic 10a Sound editing – Task 1
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Finally, export the finished track as timer1.mp3.
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Audio editing task guide 9626 Sub-topic 10a Sound editing – Task 1
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