# Data Representation - Sound Flashcards

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1
Q

What piece of hardware would you use to input sound into a computer?

A

Microphone

2
Q

How is sound stored as binary?

A
• Audio file is inputted through a microphone and broken down into thousands of samples per second,
• The more samples recorded per second the higher the quality of the audio file,
• Each sound sample is stored as Binary Data
3
Q

What is the correct order of stages in converting sound into a digital form

A - binary representation of level stored

B - microphone picks up sound waves

C - value read at specific point and rounded to a level

D - sound wave is converted to an electrical analogue signal

A

B - microphone picks up sound waves

D - sound wave is converted to an electrical analogue signal

C - value read at specific point and rounded to a level

A - binary representation of level stored

4
Q

What is sample rate?

A

The number of samples taken…per second

5
Q

What unit is sample rate measured in?

A

Hertz (Hz)

6
Q

What is measured when the wave is sampled?

A

Amplitude

7
Q

What does a sample represent?

A

Each sample represents the amplitude of the digital signal at a specific point in time

8
Q

The amplitude of a sound wave is…

A

how high the wave is from the crest or trough

9
Q

Explain the process of sound sampling

A
• Sampling is a method of converting an analogue sound signal into a digital file.
• At specific intervals (frequency) a measurement of the amplitude (bit depth) of the signal is taken.

-The higher the sampling rate / bit depth the better the quality of the sound file

10
Q

Describe how sound samples are stored

A
• The amplitude of each sound sample is converted into the equivalent binary number.
• The whole collection of data (binary numbers) is then stored in a digital file.
11
Q

Why does sound need to be sampled to be stored in a computer?

A

Sound exists as waves – however as computers only understand binary values this needs to be converted into such

12
Q

Define sampling resolution

A

number of bits…used to represent a sample

13
Q

What 3 things happen if you increase the sample rate?

A
• Better quality of recording
• Needs greater storage space
• Larger file size
14
Q

Why does increasing the sample rate increase sound quality?

A
• More detail about where the waves are recorded

- the shape of the sound wave is captured more accurately

15
Q

What sample rate is used for CD quality sound?

A

44,100 Hz

16
Q

What is the sample rate of telephone networks and VOIP services?

A

8 kHz

17
Q

Why do CDs provide better quality audio than telephone networks?

A

CDs have a higher sample rate (44,100 Hz) than telephone networks (8hz)…this leads to higher quality audio because there is more information about the audio

18
Q

What is Bit Rate?

A

The number of bits used per second of audio

19
Q

What are Bit rates are usually measured in?

A

kilobits per second (kbps)

20
Q

What is meant by bit depth?

A

The number of bits used to store each sound sample

21
Q

What happens when you increase bit depth when recording sound digitally?

A

The higher the bit depth, the higher the quality of the audio

22
Q

What happens when you decrease bit depth when recording sound digitally?

A

The lower the bit depth, the lower the quality of the audio

23
Q

How do you calculate bit rate?

A

Frequency × bit depth × channels = bit rate

24
Q

Give three examples of metadata stored in sound files

A
```Artist  Title
Track Title
Album Title
Track Number
Date Created / Year
Genre
Duration
File size
Bit rate
Sampling rate```
25
Q

How do you calculate the storage requirements for the sampled sound data.

A

Storage size = sampling rate x sampling resolution x number of seconds the (original/analogue) sound lasts

26
Q

Describe how a lossy algorithm would compress the sound file

A
• Sound files are compressed using a lossy algorithm by analysing the waveform and removing sound that cannot be heard by people.
• To increase the compression, lossy algorithms remove more data which reduces the quality of the sound file (lowers fidelity)
27
Q

How do you calculate the compression ratio.

A

Original file size divided by compressed file size

28
Q

The purpose of a Digital to Analogue converter is to…

A

convert binary data into analogue form so we can hear it via a speaker