3.5.6.5 Digital Representation of Sound. Flashcards
Describe the digital representation of sound in
terms of sample resolution.
The number of bits allocated to each sample is referred to as the sample resolution.
What does a higher sample resolution equal?
Greater audio quality but also increased file size.
How do you calculate the size of a sound sample?
Duration of the sample (seconds) x sampling rates (Hertz) x sample resolution.
To convert to bytes divide by bits.
What else will increase the space required to store an audio file?
Metadata.
Outline The Nyquist Theorem.
States that the sampling rate of a digital audio file must be at least twice the frequency of the sound. If the sampling rate is below this, the sound may not be accurately represented.
What does MIDI stand for?
Musical Instrument Digital Interface.
Describe the purpose of a MIDI.
Its a way to connect devices that make and control sound such as computers, synthesisers and samplers.
Is used with electronical musical instruments which can be connected to computers.
Describe the use of event messages in MIDI.
MIDI stores sound as a series of event messages, each of which represents an event in a piece of music.
What is an event in a piece of music?
These can be thought as a series of instructions which could be used to recreate a piece of music.
What information can event messages contain?
The duration of a note.
The instrument with which a note is played.
How loud a note is (its volume).
If a note should be sustained.
Outline the advantages of using MIDI over recording a piece of music.
Allows easy manipulation of music without loss of quality.
The instruments on which notes sound can be changed, notes can be transposed and the duration of notes can be altered.
MIDI files are smaller in size than sampled audio files are are lossless so there’s no information lost when music is stored using MIDI.
Outline the disadvantages of MIDI.
MIDI cant be used for storing speech.
Can result in a less realistic sound than sampled recordings.
