OCR
Oxford Cambridge and RSA
GCSE (9-1) Computer Science
Computer Systems
J277/01
Topic: Unit 1.2 Sound
Time allowed: 20 minutes
Centre number
Candidate number
First name
Last name
INSTRUCTIONS
Use black ink.
Answer
all
the questions.
INFORMATION
The total mark for this paper is
16
.
The marks for each question are shown in brackets [ ].
Turn over
1
Sound needs to be converted into binary to be processed by a computer.
(a)
Define the term 'Sample Rate'.
[1]
(b)
Define the term 'Bit Depth'.
[1]
2
A student records a 10-second audio clip.
The recording uses a sample rate of 3,000 Hz and a bit depth of 8 bits.
(a)
Calculate the file size of the recording in
bits
.
Show your working.
[2]
Working:
Answer:
bits
(b)
Convert your answer from part (a) into
bytes
.
[1]
Answer:
bytes
3
Describe how an analogue sound wave is converted into a digital file.
Use the terms
'amplitude'
,
'measure'
, and
'binary'
in your answer.
[3]
Turn over
4
A musician is recording a song in a studio.
They decide to increase the Bit Depth from 16-bit to 24-bit.
(a)
Explain the effect this change will have on the
quality
of the sound.
[2]
(b)
Explain the effect this change will have on the
file size
of the recording.
[2]
5
A podcast producer needs to reduce the file size of their latest episode so it can be downloaded faster. The current file is too large.
(a)
State
two
changes the producer could make to the sound file to reduce its size.
Do not use compression in your answer.
[2]
1.
2.
(b)
For
one
of the changes you identified in part (a), explain why this might negatively affect the listener's experience.
[2]
Change chosen:
Effect:
END OF QUESTION PAPER