Lecture # 23 Sound Synthesis & Sound Arithmetic

Lecture # 23 Sound Synthesis & Sound Arithmetic

Jane Fred loves A “sound font” dog loves Fred the Jane Ralph knows

MIDI - Musical Instrument Digital Interface • Object representation of music • Every sound has • Pitch (frequency of the sound) • Delay (how long after last sound start to start playing) • Duration (how long should it play) • Timbre (which instrument should it sound like?) • Guitar • Clarinet • Violin

A MIDI file • An array of notes 0 (262, 0,10,1) 1 (300, 10,10,1) 2 (262, 10, 10, 1) 3 (300, 0, 10, 1) Delay Pitch (middle C) Duration Instrument Number During performance numbers are assigned to different instruments

MIDI demo http://www.free-midi.org/midi1/v/vangelis-chariots_of_fire.mid

A MIDI file • An array of notes 0 (262, 0,10,1) 1 (300, 10,10,1) 2 (262, 10, 10, 1) 3 (300, 0, 10, 1) How do we transpose to a higher key? Increase pitch of each note

A MIDI file • An array of notes 0 (262, 0,10,1) 1 (300, 10,10,1) 2 (262, 10, 10, 1) 3 (300, 0, 10, 1) How do we make it play faster? Reduce delay and duration of each note

A MIDI file • An array of notes 0 (262, 0,10,1) 1 (300, 10,10,1) 2 (262, 10, 10, 1) 3 (300, 0, 10, 1) How do we change from guitar to flute? Assign a different instrument to that number

Synthesizing an instrument • Mix different harmonics • Add noise • Adjust Attack, Dwell, Sustain, Release

Synthesizing an Instrument • Attack - when string is plucked or note is struck • Dwell - energy left from attack • Sustain - while the note is held • Release - after player stops

Sampled / Object Sampled Object Jane loves Fred

Sound Editing and Processingwith Audacity

Edit Sound • Drag and Drop (universities-deep_thoughts.wav) • File >> Import >> Audio • Notice new track (two if it is stereo) • File >> Import >> Audio (theknack.wav) • Notice second track • Select Track • Select Time Shift action • Move Track • Mix and Render (“barnyard”: cow, horse, duck) • Play/Mute/Align • Undo (Cntrl-Z)

Edit Sound • Split • Align • Select All • Import Dance Music • Trim • Shape • Record • Sing a round/Play around • Amplify/Distort • Blend • Arithmetic with Sounds

Arithmetic on Sound • Sound is an array of amplitudes (numbers) • The higher the amplitude, the louder the sound • Adding two sounds together • Make a sound louder or softer • Blends of two sounds • Echos

Adding two sounds Laser Guns + Distress = New Sound

Adding two sounds Algorithm Laser = laser gun sound; Warn = warning message; NewSnd = new array(Laser.length); for (each index i in NewSnd) { NewSnd[i]=Laser[i]+Warn[i]; }

Adding Sounds Demo • Drag or manufacture 2 or more track • Play • Shift • Mix and Render

Making a sound louder

Amplify Sound Demo • Effects -> Amplify

Making a sound louder for (each index i in oldSound) { newSound[i]=oldSound[i]*3; }

General Amplify algorithm amp = 3.0; three times as loud for (each index i in oldSound) { newSound[i]=oldSound[i]*amp; }

General Amplify algorithm amp = 0.5; half as loud for (each index i in oldSound) { newSound[i]=oldSound[i]*amp; }

Blending two sounds Music 50% music, 50% words Words

Blending Sounds Demo • 2+ Tracks -> Effects -> Amplify • Tracks -> Mix Render

Algorithm for Blending two sounds B = blend value between 0.0 and 1.0 for (each index i in Snd1) { newSnd[i]=(1.0-B)*Snd1[i]+ B*Snd2[i]; }

Singing a Round by yourself • Row Row Row your boat • Sing in a round

Singing a round by yourself + Time delay =

Singing a round by yourself Demo • 2+ tracks -> align/shift/paste • Tracks -> Mix Render

Singing a round by yourself song = the original song; delay = how many samples to delay; newSng = new array(song.length+delay); for (each index i in song) { newSng[i] = song[i]; } for (each index i in song) { newSng[i+delay] = newSng[i+delay]+song[i]; }

Echoes • An echo occurs because sound returns delayed and softer after bouncing off of something • Original • Canyon Echo (large delay) • Room Reverb (small delay)

Echoes Demo • Audacity • Effects -> Echo

Echoes Algorithm sound = the original sound; delay = how many samples to delay; softness = 0.1; newSound = new array(sound.length+delay); for (each index i in sound) { newSound[i] = sound[i]; } for (each index i in sound) { newSound[i+delay] = newSound[i+delay] + sound[i]*softness; }

Review • Sound Synthesis (MIDI, timbre, pitch, etc) • Change Pitch • Change Tempo • Change Speed

Lecture # 23 Sound Synthesis & Sound Arithmetic