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level: Sound (NEED)

Questions and Answers List

level questions: Sound (NEED)

QuestionAnswer
Describe how bit patterns may be used to represent soundAs the amplitude of the sound being represented by a binary number Amplitude is taken at given time intervals Think of a graph
Whats Nyquist theoremSampling rate of a digital audio file = 2 X frequency For the sound for the audio to be accurate
Define MIDIIt’s a protocol for transferring digital instrumentional data
Whats the difference between analogue and digitalAnalog signal is represented by the sine waves when the digital signal is represented by square waves Analogue data is continuous, there are no limits to the values that the data can take. In contrast, digital data is discrete, meaning that it can only take particular values
Describe the principles of operation of an ADCAn ADC is used The device works by taking a reading of an analogue signal, through an analogue sensor, at regular intervals and recording the value in a process called sampling Samples are taken at a specific frequency which determines the number of samples taken per second This can then be stored digitally as a bit pattern
How do you calculate the size of a sound samplesampling rate X sample resolutuion X duration = size in bits
Describe the principles of operation of a DACA DAC is used The device reads a bit pattern representing an analogue signal and outputs an alternating, analogue, electrical current
Whats the most common use for a DACconvert a digital audio signal to an analogue signal So speakers
What are ADCs used in conjuction with?Analogue sensors
Whats are event messages in MIDIMIDIs storage of sound Each of which indenpedently represents a different musical event
Give some examples of event messages in MIDI● 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
Whats the advatages of using MIDI over a sampled recording of a piece of musicEasy manipulation of music without loss of quality MIDI files are often smaller in size than sampled audio files and are lossless so there’s no information lost when music is stored using MIDI.
Whats the disadvatages of using MIDI over a sampled recording of a piece of musicMIDI can't be used for storing speech Sometimes results in a less realistic sound than sampled recordings
Define sample rateNumber of samples per second
How is sound represented by computers?As a sequence of samples Or series of messages (MIDI)
What are the pros and cons to increasing the sampling resoltionBetter quality but greater file size
State what sample resolution isNumber of bits allocated to each sample
Explain the differences between the way in which sound is recorded for MIDI and ADC/DACStorage of sound as a series of event messages rather than samples