The same sound is recorded twice using different sample intervals.
Explain the effect of using a longer sample interval on the digital recording.
Mark scheme
Award up to two marks for a linked explanation such as:
- Fewer samples are taken every second (1) so less detail of the sound wave is captured (1)
- Fewer samples are taken every second (1) so the file is smaller/uses less storage space (1)
- The wave is measured less often (1) so parts/changes in the wave between samples are missed (1)
For both marks, the expansion must follow/associate with the statement.
The 'fewer samples are taken/measured less often' point can only be credited once; the second mark is for a valid expansion linked to it.
Do not accept restating the question, e.g. 'the time between measurements is longer' or 'the sample interval is longer', as either the point or the expansion.
Do not accept 'the sample rate is lower' as the expansion, as this says the same thing as a longer sample interval.
Do not accept 'the sound is lower quality/less accurate' on its own without saying what is lost, e.g. less detail of the wave captured/parts of the wave missed.
Do not accept answers about using fewer bits per sample or about compression, as these do not follow from the sample interval.
Example answers and how they were marked
Fewer samples are taken every second, so less detail of the sound wave is captured and the recording is less accurate.
Why: Point (fewer samples each second) (1) with linked reason (less detail of the wave captured) (1).
Fewer samples are taken every second.
Why: Creditworthy point (1) but no linked effect on the detail or size of the recording, so only one mark.
The samples are stored using fewer bits, so the sound is less accurate.
Why: Describes a smaller bit depth rather than a longer sample interval, so no mark is awarded.