Electronic Music

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Electronic Music
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Overview

• What youve seen so far
• Olden Days
• MIDI
• Sampling
• FM Synthesis
• ADSR

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What Youve Seen

• So far, weve digitized audio
• Sampling rate
• Bit depth
• Weve recorded a live sound
• Playback is represented by the levels of the
  speaker

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ABBA Revisited
MIDI
MP3
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The Old Days

• First Keyboards
• had oscillators (circuits) to generate sounds
• Usually monophonic (one note at a time)
• Second generation
• Used FM synthesis (later)
• Usually polyphonic (multiple notes at a time)
• Had to record keyboard sounds to tape

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MIDI(Musical Instrument Digital Interface)

• MIDI a method for representing sounds
  electronically
• Became popular in the 80s
• Send 16 different channels (tracks) at one time
• Have a total of 128 possible instruments

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The Keyboard

• The MIDI Keyboard
• No audible sounds
• Generates a series of
• 1s a 0s (on/off)
• Signals represent
• Note, loudness
• Length, type of instrument
• Signals come out of the keyboard and usually go
  into a sequencer

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The Sequencer

• Can be a PC
• Responsible for recordingindividual tracks of
  music
• Responsible for playback
• Receives input from keyboard
• Sends output to synthesizer

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The Synthesizer

• Receives 1s and 0s fromthe sequencer
• Interprets the 1s and 0sto produce audible
  sounds
• Piano
• Drums
• Saxophone
• Sounds are sent to speakers

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Speakers

• Like you haventseen these before

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MIDI
01101101000110
0 1 0
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MIDI vs Digital Recording

• MIDI
• Smaller file size (like 10-20K)
• Song sounds different on every sound card
• No singing allowed!
• Digital Recording
• Larger file size (like 5M)
• Sound is close approximation to real thing

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Sampling

• There are two main approaches to synthesis
• Sampling
• FM Synthesis
• Sampling
• A sample is a recording of actual
  instrument/sound
• Samples are taken at certain intervals
• Samples are then shifted up or down depending on
  the note

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Sampling
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FM Synthesis

• Basic waves
• Sine
• Square
• Saw
• Triangle
• Noise

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FM Synthesis

• Start with basic waveform, and have one wave
  modulate the other
• Heres volume modulation
• 440 sine wave, control 2Hz
• 440 sine wave, control 880Hz
• 440 sine wave, control 3KHz

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ADSR(Attack, Decay, Sustain, Release)

• Use a graph to describe the shape of the sound

A
D
S
R
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ACID

• Good for non-musical people
• Download Loops
• Mix loops together
• Outputs a complete .wav file

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