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12 - Representing Sound

1. MP3 (formally MPEG-1 Audio Layer III or MPEG-2 Audio Layer III) is an audio coding format for __________ audio

clockword

old fashioned

digital

metric

2. A "real" sound that we hear every day (like the sound of your friend's voice) is _____________

both analogue and digital in nature

digital in nature (comprised of 1s and 0s)

metallic in nature (in reality sound is made up of tiny metal bits)

(wave like) analogue in nature (tones and rhythms blend smoothly together)

3. If a sound has to be handled by a computer any sound source has to be converted to ____________________

a set of binary numbers

a set of CPU signals

a set of waves

None of the above

4. What is the difference between analogue and digital recorded sounds?

You do not need to watch the video to answer the question but to gain a more advanced understanding of this topic, it is worth viewing.

An analog sound file is stored in bits where as a digital file is more advanced and wave like

An analog signal is continuous, think: a wave. Digital refers to being stored in bits

An analog sound file is less like the original sound as it is made up of digital bitcoins

None of the above

5. Digitising' the sound (making it digital) by using an input device connected to your computer is called:

ghosting the sound

sampling the sound

bitling the sound

digitalising the sound

6. One device that is involved in capturing analogue sound and converting it into a digital file for use by a PC is a:

modem

mouse

microphone

internet router

7. An input device senses incoming sound, it converts the sound into an electrical signal, and then this signal is ……..

Image Source: ICT Lounge

passed on to the ADC (analogue to digital converter) in the sound card

passed on to the CPU to convert the signal into binary bytes

passed on to the monitor to interpret the sound and record it directly

passed on to the operating system of the PC which will convert the sound into waves

8. A sound card has two jobs. 1. Convert analogue signals to digital for storage and 2…….

convert stored digital signals into electrical signals to send to the speakers

convert digital signals into 24 bit patterns which are read by the speakers

convert analogue signals into sound waves so the human ear can hear them

convert digital signals into binary numbers so they can play accurately

9. What are the ADC and DAC?

Analogue to Digital Converter and the Digital to Analogue Converter

Neither of these exist

They are both binary pattern sequences that are used to encode sound

They are both sound cards

10. What needs to happen in order to play a sound (via a computer speaker)?

File opened. Binary numbers fed through the ADC. Speakers use a sound card to re-convert to bits

File opened. Binary numbers fed through DAC. Amplification applied to power the speakers and play sound

File opened. Binary numbers passed through the speakers directly

None of the above

11. Sound is measured in cycles per second or _______________________

Bits

Amps

Watts

Hertz

12. The higher the frequency (in hertz) the….

the quieter it is

lower pitched it sounds

the higher pitched it sounds

None of the above

13. Tone is one thing, but loudness of sound also matters! Because sound is a ________, the loudness is the ________ of the wave

freight

height (amplitude)

depth

width

14. ______________ is a method of converting an analogue sound signal into a set of binary numbers that are stored in digital format.

sampling

frequenting

bimping

amplituding

15. What is the sampling frequency or rate?

Note: The following video is informative - do watch it if you can - but you don't need it specifically for this question.

the rate at which sound is stored as waves and the length changes

This is the rate at which samples are taken (stated in Kilohertz (thousand times per second)

None of the above

the rate at which binary sequences are converted into waves

16. There is a _________________ at which samples need to be taken in order to faithfully reproduce the original signal

minimum bit rate (expected number of bits)

maximum sampling rate

dim rate

minimum sampling rate (at least twice the highest frequency in the signal)

17. For a CD that has sound going up to about 20KHz, the minimum sampling rate is…

140 KHz

20KHz

40KHz

70KHz

18. Getting the sampling rate right is important for capturing…..

binary bits

sampling keys

multiple waves

frequency information

19. Another thing that is important to consider in this unit is the ______________

accuracy of the number of bits

light vs sound dilemma

accuracy of the measurement

binary vs wave duality

20. The number of bits which are used per sample is called the:

wave amplitude

Sampling bit depth

binary bit wave

Accuracy of binary numbers

21. Higher bit depth audio will sound …………………..

None of the above

better than a lower one

worse than a lower one

the same as a lower one

22. As bit depth and sample rate increase…..

more information is captured resulting in higher quality audio

more information is captured, which causes blockage, and reduces audio quality

the same amount of information is captured, which is why sound always sounds the same

less information is captured resulting in lower quality audio

23. Sampling resolution: In the diagram above, a sample can only have _____________ as represented by the 2 bit number

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eight values

three values

two values

four values

24. In the image below The 11KHz sound sample is far lower quality than the 44 KHz sample, but on the other hand …….

the number of bits per wave is reduced

the file size is 30 times smaller.

the file size is 30 times bigger

the Khz is increased exponentially

25. Whenever a sound is sampled, you should ensure that the recording system________________otherwise the re-played sound will have some serious distortion.

can convert itself into bits

can obliterate itself

can handle the largest signal and the smallest signal,

can handle only the smallest signal

26. The bit rate is the amount of information required to describe one second of sound. The formula is:

Bit rate = bit depth x channel rate

Bit rate = bit depth + number of channels + sample rate

Bit rate = sample rate x bit depth x number of channels

Bit rate = sample rate x bit rate x sample rate x 2

27. To work out the bit rate for one second of audio you would have to:

Do the following to find out the bit rate for 
one second of audio: 
==================================================
Multiply the number of samples
taken in one second by the number of bits needed 
for each sample for each audio channel (then multiply 
by no. of channels)

TRUE OR FALSE?

TRUE

FALSE

28. The unit for bit rate is:

bits per mile

samples per second

bits per second

Hertz

29. A CD quality stereo audio recording with two channels would require: Bit rate = 44,100 x 16 ______________

The ideal sample rate
=====================
The sample rate of 44100Hz is standard
for music and CDs and is the
 ideal rate to record all your podcast 
audio at.

Note: Sound designers in game, film, and television 
will mainly work in 48000Hz, though some work 
as high as 96000Hz.

x 20 = 2000,00021231 bits per mile

x 2 = 1,411,200 bits per second (1.4 Mbps)

x 3 = 150,22,2343 samples per second

x 6 = 1882919281 bits per second

30. The disadvantage of having a very high bit rate is ….

producing very large file sizes

producing very loud audio files

producing very quiet audio files

producing very small file sizes

31. You can reduce the bit rate without sacrificing too much quality by using a technique called:

sacrificialsounding

sampling

compression

meshing

32. To work out the total size of an audio file, you….

take the bit rate and multiply it by the number of bits contained in the file itself

take the bit rate and multiply it by itself

take the bit rate and multiply it by the length of the file in seconds

take the bit rate and multiply it by the sampling rate + bit depth

33. Complete the formula:

file size =

length * sample rate

bit rate * length

sample rate + bit rate + sample depth

bit rate * 256

34. Given the followig details, what is the storage requirement?

Sampling rate: 44.1 Khz 
Sample bit depth: 16 bits; 
Recording time: 180 seconds

Storage = Sample rate x bit depth x channels x time
=

2000 bits

200.21 mebgabits

127 million bits

3423 Hertz

35. As there are 8 bits to a byte, the storage for an uncompressed 3 minute CD quality recording is:

Sampling rate: 44.1 Khz 
Sample bit depth: 16 bits; 
Recording time: 180 seconds

Storage = Sample rate x bit depth x channels x time
=

bytes of storage = 127 Megabits / 8 = 31 Megabytes

bytes of storage = 100 / 2 = 50 Megabytes

None of the above

bytes of storage = 32 / 2 = 16 Megabytes

36. (Most) humans use two ears to hear. A channel is a single sound stream.

FALSE

TRUE

37. Mono sound has information about only a single source or single channel

TRUE

FALSE

38. Stereo sound also called ________ sound will have ______ channels, to make use of multiple speakers. Each channel needs its own samples

stereo / multiple

multiple / sony

configured / strero

multiple / mentored

39. In order for an audio player to play back a sound file, the file needs meta data (extra information) on top of the samples.

Which of the following in the list
count as basic meta data (embedded
at the beginning of the file)

1. Sample rate
2. Exact number of bits held
3. Bit rate
4. Name of the sampler
5. Length
6. Name of the device used to sample
7. Codec

1,2,3,4,5

all of the above

1,3,5,7

none of the above

40. The longer the sampling lasts the smaller the file will be

TRUE

FALSE

41. A bit depth of 8 bits allows 256 levels of the wave to be measured

FALSE

TRUE

42. Doubling the bit depth will ______________________________

triple the file size

None of the above

half the file size

double the file size

43. The higher the bit depth, the worse the percieved quality of sound.

FALSE

TRUE

44. Bit rate (bits per second) is a product of sample rate, channel compression rate and four times the sample bit depth

TRUE

FALSE

45. An uncompressed file format is WAV and a compressed format is a MP3

FALSE

TRUE

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