Analogue and Digital Recording

Question 1

What are the only values a digital signal can possess?

Answer 1

0 or 1

Question 2

What does the process of analogue to digital conversion involve?

Answer 2

Taking digital samples of the momentary amplitude of a waveform

Question 3

In analogue to digital conversion, what is a continuous analogue signal converted into?

Answer 3

A series of binary numbers

Question 4

With regards to analogue to digital conversion, what is the sample rate?

Answer 4

The number of times the amplitude of the analogue signal is read

Question 5

In analogue to digital conversion, what is 1Hz equal to?

Answer 5

1 sample of the waveform’s amplitude taken every second

Question 6

What sample rate is CD quality?

Answer 6

44.1kHz

Question 7

What sample rate is DVD quality?

Answer 7

48kHz

Question 8

Why is there an argument against recordings at a sample rate higher than 48kHz sounding better?

Answer 8

Because the limitations of human hearing mean you would very unlikely hear any difference

Question 9

What effect does the sample rate have on the frequency response of equipment?

Answer 9

The higher the sample rate, the greater the highest frequency captured

Question 10

What is Nyquist’s theorem?

Answer 10

The sample rate of a digital system should be a minimum of twice the highest frequency captured

Question 11

What occurs when the sample rate is not high enough?

Answer 11

Aliasing

Question 12

What happens to frequencies above the Nyquist frequency?

Answer 12

They are captured and incorrectly recreated within the audible range below the Nyquist frequency

Question 13

What does the incorrect recreation of frequencies above the Nyquist frequency manifest as?

Answer 13

Artefacts

Question 14

In analogue-digital conversion, what is the bit depth?

Answer 14

The level of detail the amplitude is measured to for each sample

Question 15

What effect does a higher but depth have on the signal?

Answer 15

The greater the bit depth, the greater the dynamic range, and therefore the signal-to-noise ratio

Question 16

What is the bit depth of CD quality?

Answer 16

16-bit

Question 17

What bit depth is commonly seen with digital audio?

Answer 17

24-bit

Question 18

Why is a bit depth of 24 useful when working on a project?

Answer 18

The noise on multiple tracks soon adds up

Question 19

With regards to analogue-digital conversion, what is dithering?

Answer 19

The introduction of small amounts of unobtrusive, randomly-generated noise into the conversion process

Question 20

In analogue-digital conversion, what effect does dithering have?

Answer 20

It randomises the effect of quantisation error

Question 21

True or false: analogue signals are less susceptible to interference than digital signals

Answer 21

False

Question 22

What happens if an analogue signal picks up noise?

Answer 22

It forms part of the waveform

Question 23

What happens if a digital signal picks up noise?

Answer 23

It doesn’t degrade in quality, as it still identifies as 0 or 1