Storing Sound Flashcards
What are analogue signals?
Pieces of continually changing data.
Sound is recorded by a microphone as what?
An analogue signal.
Why do analogue signals need to be converted into digital data and how?
So that computers can read and store sound files. This is done by analogue to digital converters which are found in most modern recording devices.
What is sampling?
The process of converting analogue to digital.
How do we convert the analogue to digital data?
Sample the amplitude of the wave at regular intervals. The amplitude can only take certain values depending on the bit rate. Once the device has sampled the recording iy creates the curve digitally.
How is digital data and analogue data similar and different?
Similar:
- the same shape
Different:
- not continuous, its lost a lot of data
How can the digital data be improved?
By taking samples more regularly - most music isn’t sampled every second but every couple of milliseconds.
What factors can affect the size and quality of sound files?
- sampling intervals
- sampling frequency
- sample size
- bit rate
What are sampling intervals?
The gaps between each point where the analogue recording is sampled.
What is the sampling frequency (or sample rate)?
How many samples you take in a second. Usually measured in kilohertz (kHz).
What is the sample size?
The number of bits available for each sample.
What is bit rate?
The number of bits used per second of audio.
How is bit rate calculated?
bit rate = sampling frequency x sample size
What effect does increasing the sampling frequency have?
- analogue recording is sampled more often
- sampled sound will be better quality
- more closely match the original recording
What effect does increasing the sample size have?
- digital file picks up quieter sounds even if they’re happening at the same time as louder ones
- sampled sound closer quality to the original recording.
