Analogue sound waves and digital sound

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Which describes a real sound wave?

A Analogue: its amplitude changes smoothly and continuously

B Digital: its amplitude is stored as separate binary numbers

2. A computer can directly store which kind of data?

A A smooth, continuous wave

B Separate (discrete) binary numbers

3. A microphone captures a sound wave. What must happen before the computer can process it?

A It must be converted into discrete digital values

B It can be processed straight away as an analogue wave

4. What does the microphone do in the process of recording sound?

A It captures the sound wave so it can be measured

B It stores the sound as binary on the hard drive

5. Which statement about amplitude in an analogue wave is correct?

A It can only jump between a few fixed whole numbers

B It changes smoothly and can take any value in a range

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1analogue		Asound wave -> microphone -> analogue to digital -> binary
2digital		BIt is analogue sound that has a smoothly changing amplitude. Digital sound is made of separate, discrete values.
3A microphone captures a continuous sound wave, and the wave must then be converted into binary numbers		CData stored as separate (discrete) binary values, so a computer can process it
4A computer can only store separate numbers, so the smooth wave is stored as a list of discrete values		Dwave = 0.0 ... 1.0 -> stored = 0, 3, 5, 3, 0
5A computer stores the analogue wave directly		EA computer cannot store an analogue wave directly. It can only store discrete binary values, so the wave must first be converted to digital.
6Digital sound has a smoothly changing amplitude		FA signal that changes smoothly and continuously, like the amplitude of a sound wave, with infinitely many possible values

Definitions

analogue to digital

Fill in the Blanks

Complete each line of code by filling in the missing parts.

wave ← __________.capture()

digital ← _______(wave)

OUTPUT wave._________

_______ ← [3, 7, 12, 9]

computer.store(______)

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A wave = microphone.capture()

B samples = []

C samples.append(wave)

D print(samples)

Question 2

A mic = Microphone()

B wave = mic.capture()

C adc = Converter()

D digital = wave

Question 3

A wave = 'analogue'

B computer = 'digital'

C convert = wave == computer

D print(convert)

Question 4

A amplitude = 'separate'

B computer_values = 'separate'

C print(amplitude)

Question 5

A mic = Microphone()

B wave = mic.capture()

C levels = measure(wave)

D store(levels, 'analogue')

Answer Key

Analogue sound waves and digital sound

Section A: Quick Questions

A — Analogue: its amplitude changes smoothly and continuously

B — Separate (discrete) binary numbers

A — It must be converted into discrete digital values

A — It captures the sound wave so it can be measured

B — It changes smoothly and can take any value in a range

Section B: Match the Pairs

analogue → A signal that changes smoothly and continuously, like the amplitude of a sound wave, with infinitely many possible values

digital → Data stored as separate (discrete) binary values, so a computer can process it

A microphone captures a continuous sound wave, and the wave must then be converted into binary numbers → sound wave -> microphone -> analogue to digital -> binary

A computer can only store separate numbers, so the smooth wave is stored as a list of discrete values → wave = 0.0 ... 1.0 -> stored = 0, 3, 5, 3, 0

A computer stores the analogue wave directly → A computer cannot store an analogue wave directly. It can only store discrete binary values, so the wave must first be converted to digital.

Digital sound has a smoothly changing amplitude → It is analogue sound that has a smoothly changing amplitude. Digital sound is made of separate, discrete values.

Section C: Definitions

analogue to digital — A sound wave is analogue: its amplitude changes smoothly. A computer stores only separate binary numbers, so the wave a microphone captures must be converted into discrete digital values.

Section D: Fill in the Blanks

wave ← microphone.capture()

digital ← convert(wave)

OUTPUT wave.amplitude

digital ← [3, 7, 12, 9]

computer.store(binary)

Section E: Spot the Error

C — The wave is analogue and continuous, so it cannot be stored as it is. Each item added must be a separate measured number, so it should be samples.append(measure(wave)).

D — The captured wave is still analogue. It must be passed through the converter to become digital values, so the line should be digital = adc.convert(wave).

C — Conversion is needed when the wave type is different from the type the computer stores. The test should use != (not equal), not ==.

A — The amplitude of an analogue sound wave changes smoothly. It is the computer's stored values that are separate, so line 1 should be amplitude = 'smooth'.

D — A computer can only store digital data as binary numbers. The measured levels must be stored as 'binary', not 'analogue'.