Data Representation - Sound Flashcards
What piece of hardware would you use to input sound into a computer?
Microphone
How is sound stored as binary?
- 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
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
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
What is sample rate?
The number of samples taken…per second
What unit is sample rate measured in?
Hertz (Hz)
What is measured when the wave is sampled?
Amplitude
What does a sample represent?
Each sample represents the amplitude of the digital signal at a specific point in time
The amplitude of a sound wave is…
how high the wave is from the crest or trough
Explain the process of sound sampling
- 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
Describe how sound samples are stored
- 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.
Why does sound need to be sampled to be stored in a computer?
Sound exists as waves – however as computers only understand binary values this needs to be converted into such
Define sampling resolution
number of bits…used to represent a sample
What 3 things happen if you increase the sample rate?
- Better quality of recording
- Needs greater storage space
- Larger file size
Why does increasing the sample rate increase sound quality?
- More detail about where the waves are recorded
- the shape of the sound wave is captured more accurately
What sample rate is used for CD quality sound?
44,100 Hz
What is the sample rate of telephone networks and VOIP services?
8 kHz
Why do CDs provide better quality audio than telephone networks?
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
What is Bit Rate?
The number of bits used per second of audio
What are Bit rates are usually measured in?
kilobits per second (kbps)
What is meant by bit depth?
The number of bits used to store each sound sample
What happens when you increase bit depth when recording sound digitally?
The higher the bit depth, the higher the quality of the audio
What happens when you decrease bit depth when recording sound digitally?
The lower the bit depth, the lower the quality of the audio
How do you calculate bit rate?
Frequency × bit depth × channels = bit rate
Give three examples of metadata stored in sound files
Artist Title Track Title Album Title Track Number Date Created / Year Genre Comments Copyright Duration File size Bit rate Sampling rate
How do you calculate the storage requirements for the sampled sound data.
Storage size = sampling rate x sampling resolution x number of seconds the (original/analogue) sound lasts
Describe how a lossy algorithm would compress the sound file
- 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)
How do you calculate the compression ratio.
Original file size divided by compressed file size
The purpose of a Digital to Analogue converter is to…
convert binary data into analogue form so we can hear it via a speaker
