Computing - Sound
AQA Computer Science 2022
Analogue and digital signals
What is the main difference between an analogue and digital signal?
Analogue signals are continuous while digital signals are discrete.
In one sentence, how does a digital-to-analogue converter for sound work?
Sound is captured by a microphone which is sampled at regular intervals and these samples are converted to binary.
Sampling rate and resolution
The frequency at which samples of a sound are taken is called?
The sampling rate.
When an analogue sound signal is being converted to digital, what value is sampled?
Amplitude/voltage.
What is sample resolution?
The amount of bits used to record each sample.
What is the benefit of a higher sample resolution?
More accurate representation of the analogue sound.
What is the formula for file size of a sound?
The Nyquist Theorem
What is the symbol representation of Nyquist Theorem?
What does $f _ {\text{max}}$ stand for in the Nyquist Theorem?
The max frequency in the sound.
What does the Nyquist Theorem state?
That the sample rate should be _ _ over _ _ two times the highest frequency in order to create an accurate sample.
The theorem that the sample rate should be _ _ over _ _ two times the highest frequency is called?
The Nyquist Theorem
Why are CDs sampled at $44.1kHz$?
Because the max of human hearing is $22kHz$, so it’s over double.