OCR GCSE Computer Science (J277) · Computer systems (Paper 1) › Memory and storage › Data storage
Practise Sound. 12 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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A short mono alert sound is recorded for 2 seconds at a sample rate of 8000 Hz with a bit depth of 8 bits. Calculate the file size in bits.
128 000 bits
Sample questions
Written for this site in the style of OCR exam questions. They are not taken from real past papers.
Question 1Easy3 marks
(a) State what is meant by the sample rate of a sound recording.[1]
(b) State what is meant by the bit depth (sample resolution) of a sound recording.[1]
(c) Which one of the following would reduce the file size of a sound recording? Tick (✓) one box.[1]
Increasing the bit depth
Increasing the length of the recording
Reducing the sample rate
Increasing the sample rate
Show the answer and mark scheme
(a)
the number of samples taken per second
(b)
the number of bits used to store each sample
(c)Answer: Reducing the sample rate
Question 2Medium5 marks
(a) Explain how increasing the sample rate affects the quality of the playback.[2]
(b) Explain how increasing the sample rate affects the file size.[1]
(c) Explain how increasing the bit depth affects the quality of the playback.[2]
Show the answer and mark scheme
(a)
more samples are taken each second
so the digital recording is closer to / a more accurate copy of the original sound
(b)
there are more samples to store, so the file is larger
(c)
each sample has more bits, so there are more possible values
so each sample is recorded more accurately / closer to the real amplitude
Question 3Hard6 marks
A podcast producer records speech in mono at a sample rate of 44,100 Hz with a bit depth of 16 bits.
(a) The producer decides to reduce the sample rate to 22,050 Hz. Explain why this is a sensible choice for a podcast that contains only speech.[3]
(b) Calculate the file size of a 30-minute episode recorded in mono at 22,050 Hz with a bit depth of 16 bits. Give your answer in MB. Use 1 MB = 1,000,000 bytes. Show your working.[3]
Show the answer and mark scheme
(a)
halving the sample rate halves the file size
speech does not need very high quality to be clear / the voice is still captured well enough
listeners can download episodes faster
episodes use less of the listeners' storage / data allowance