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Sound of Music How It Works Session 1 Building Blocks OLLI at Illinois Spring 2020 D. H. Tracy [email protected] This pdf handout does not contain the animations or sounds of the original presentation.

Transcript of Sound of Music - olli.illinois.eduolli.illinois.edu/downloads/courses/2020 Spring Courses/Sound of...

Sound of MusicHow It Works

Session 1Building Blocks

OLLI at Illinois

Spring 2020D. H. Tracy

[email protected]

This pdf handout does not contain the

animations or sounds of the original presentation.

Course Outline

1. Building Blocks: Some basic concepts

2. Resonance: Building Sounds

3. Hearing and the Ear

4. Musical Scales

5. Musical Instruments

6. Singing and Musical Notation

7. Harmony and Dissonance; Chords

8. Combining the Elements of Music

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Session 1 Outline: Building Blocks

1/27/20 Sound of Music 1 5

Jargon

• We’ll try to avoid Jargon (as much as possible)

• Music has a very long history

– Vocabulary, concepts, notation, even instruments have deep roots

– Lots of baggage…Legacy terminology

– Potential for obscuration or confusion!

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Building Blocks

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Demo

Books

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2010

Both Authors areScientists

andMusicians

More Books

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2008

SmartPhone Apps

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Advanced Spectrum Analyzer Pro

SmartPhone Apps

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Advanced Spectrum Analyzer Pro

Toon(iOS)

Building Blocks

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Elements of Music

• Rhythm

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Thommy Puchplays Rumba Clave on djembe drum

Elements of Music

• Rhythm

• Melody

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Tchaikovsky Swan Lake Easy Notes Sheet Music for Violin Flute Oboe

TchaikovskyOpus 20 Swan Theme A minor

Beethoven Pathetique – Piano Sonata #8

Elements of Music

• Rhythm

• Melody

• Harmony

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Harmony refers to notesplayed simultaneously

Vince Guaraldi -- Linus and Lucy

Beethoven Pathetique – Piano Sonata #8

ABBA Waterloo

Elements of Music

• Rhythm

• Melody

• Harmony

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Elements of Music

• Rhythm

• Melody

• Harmony

• Tonality

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Tchaikovsky: Swan Lake Theme (A minor)

A

Phrase starts at pitch A, then

eventually returns “home” to A

Building Blocks

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Sound Waves in Air

Institute of Sound & Vibration Research, Southampton Univ.

Velocity:

1000 ft/sec(300 m/s)

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Velocity:

1000 ft/sec(300 m/s)

Sound Waves in Air

Institute of Sound & Vibration Research, Southampton Univ.

Longitudinal WaveAir molecules move

back and forth along direction of wave

propagation

Air Pressure bobs up and down as waves pass by

any point

Sound Wave Reflection

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Hard Wall

Sound Wave Diffraction

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When hole is small compared to wavelength, more diffraction

Building Blocks

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Types of Sound Waves

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Non-periodic

Periodic

~ 1/20 sec

3.8ms

Sine

0 0.01 0.02 0.03 0.04 0.05

100 Hz

200 Hz

300 Hz

303 Hz

400 Hz

500 Hz

600 Hz

800 Hz

1000 Hz

2000 Hz

4000 Hz

Sine Waves Characterized by Frequency

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Frequency:

Vibrations per Secondor

Cycles Per Second

1857-1894

As of 1960, officially changed to

Hertz

0 0.01 0.02 0.03 0.04 0.05

100 Hz

200 Hz

300 Hz

303 Hz

400 Hz

500 Hz

600 Hz

800 Hz

1000 Hz

2000 Hz

4000 Hz

Sine Waves Characterized by Frequency

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100 Hz

200 Hz

300 Hz

303 Hz

400 Hz

500 Hz

600 Hz

800 Hz

1000 Hz

2000 Hz

4000 Hz

0 0.01 0.02 0.03 0.04 0.05

100 Hz

200 Hz

300 Hz

303 Hz

400 Hz

500 Hz

600 Hz

800 Hz

1000 Hz

2000 Hz

4000 Hz

Sine Waves Characterized by Frequency

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Your perception of PitchCorrelates with Frequency

Sinusoidal Sound Wavesare also known as

Simple Tones orPure Tones

0 0.01 0.02 0.03 0.04 0.05

100 Hz

200 Hz

300 Hz

303 Hz

400 Hz

500 Hz

600 Hz

800 Hz

1000 Hz

2000 Hz

4000 Hz

Sine Waves Characterized by Frequency

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Your perception of PitchCorrelates with Frequency

Sinusoidal Sound Wavesare also known as

Simple Tones or Pure Tones

These Pure Tones are rarein music and natureMostly Electronic

0 0.01 0.02 0.03 0.04 0.05

100 Hz

200 Hz

300 Hz

303 Hz

400 Hz

500 Hz

600 Hz

800 Hz

1000 Hz

2000 Hz

4000 Hz

Sine Waves Characterized by Wavelength

1/27/20 Sound of Music 1 35Institute for Vibration & Sound Research, Southampton

f

0 0.01 0.02 0.03 0.04 0.05

100 Hz

200 Hz

300 Hz

303 Hz

400 Hz

500 Hz

600 Hz

800 Hz

1000 Hz

2000 Hz

4000 Hz

Sine Waves Characterized by Wavelength

1/27/20 Sound of Music 1 36Institute for Vibration & Sound Research, Southampton

f

Examples:

f = 27.5 Hz 40 ft

f = 262 Hz 4 ft

f = 4186 Hz 3 in

0 0.01 0.02 0.03 0.04 0.05

100 Hz

200 Hz

300 Hz

303 Hz

400 Hz

500 Hz

600 Hz

800 Hz

1000 Hz

2000 Hz

4000 Hz

Sine Waves Characterized by Wavelength

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Examples:

f = 27.5 Hz 40 ft

f = 262 Hz 4 ft

f = 4186 Hz 3 in

Building Blocks

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Real Musical Notes are not Pure Sine Waves

• Complex tones

– Fundamental frequency f0

– Several (or many) higher frequencies(Overtones or Partials)

• Usually multiples of f0 called

Harmonics

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Complex Tone

Real Musical Notes are not Pure Sine Waves

• Complex tones

– Fundamental frequency f0

– Several (or many) higher frequencies(Overtones or Partials)

• Usually multiples of f0 called

Harmonics

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Complex Tone

Fundamental Tone

2nd Harmonic

3rd Harmonic

4th Harmonic

5th Harmonic

6th Harmonic

7th Harmonic

Musical Instruments and Nature Rarely Make Sine Waves

2/2/2017 Hear All About It 41

Building Blocks

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Visualization of Sound

Two main approaches:

• Waveform Display

• Spectrum Display

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0 0.005 0.01 0.015 0.02 0.025 0.03

Sou

nd

Pre

ssu

re →

Time (seconds)

Visualization of Sound: Spectrum

0 0.005 0.01 0.015 0.02 0.025 0.03

Sum

200 Hz

400 Hz

600 Hz

800 Hz

1000 Hz

1200 Hz

1400 Hz

• Remember how our complex waveform was built of sinusoidal harmonics?

• We could just list the constituent Partials:

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Partial #

Frequency (Hz)

Amplitude

1 200 100%

2 400 71%

3 600 40%

4 800 35%

5 1000 16%

6 1200 18%

7 1400 6%

Visualization of Sound: Spectrum

0 0.005 0.01 0.015 0.02 0.025 0.03

Sum

200 Hz

400 Hz

600 Hz

800 Hz

1000 Hz

1200 Hz

1400 Hz

• Remember how our complex waveform was built of sinusoidal harmonics?

• We could just list the constituent Partials:

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Partial #

Frequency (Hz)

Amplitude

1 200 100%

2 400 71%

3 600 40%

4 800 35%

5 1000 16%

6 1200 18%

7 1400 6%

0

0.2

0.4

0.6

0.8

1

1.2

0 200 400 600 800 1000 1200 1400

Am

pli

tud

e →

Frequency (Hz)

Frequency Spectrum of Our Complex Tone

P1

P2

P3 P4

P5 P6P7

…Or draw a graph of the Table

Visualization of Sound

Two main approaches:

• Waveform Display

• Spectrum Display

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0 0.005 0.01 0.015 0.02 0.025 0.03

Sou

nd

Pre

ssu

re →

Time (seconds)

0

0.2

0.4

0.6

0.8

1

1.2

0 200 400 600 800 1000 1200 1400

Am

pli

tud

e →

Frequency (Hz)

Frequency Spectrum of Our Complex Tone

Visualization of Sound

Two main approaches:

• Waveform Display

• Spectrum Display

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0 0.005 0.01 0.015 0.02 0.025 0.03

Sou

nd

Pre

ssu

re →

Time (seconds)

0

0.2

0.4

0.6

0.8

1

1.2

0 200 400 600 800 1000 1200 1400

Am

pli

tud

e →

Frequency (Hz)

Frequency Spectrum of Our Complex Tone

0

200

400

600

800

1000

1200

1400

1600

1 1 2 2

Fre

qu

en

cy (H

z) →

200 Hz Fundamental + Harmonics

F

H2

H3

H4

H5

H6

H7

Amplitudes Indicated

by color or line width

Visualization of Sound

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Demo failed due to software problem

Building Blocks

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Superposition of Sound Waves

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• Waves pass through one another without disruption

• Where they overlap, Superposition applies:--Pressures add up

Two sound sources of different frequencies

Superposition of Sound Waves

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• Waves pass through one another without disruption

• Where they overlap, Superposition applies:--Pressures add up

Superposition of Sound Waves

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• Waves pass through one another without disruption

• Where they overlap, Superposition applies:--Pressures add up

0 0.005 0.01 0.015 0.02 0.025 0.03

Pre

ssu

re →

Time →

Two Waves Passing by a Fixed Point

SUM

Sometimes they add up to a bigger amplitude, but sometimes they cancel each other

Building Blocks

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Phase: Delayed Waves

1/27/20 Sound of Music 1 550 0.005 0.01 0.015 0.02

Phase Shifted Waves

30°

90°

180°

270°

360°

360b

• Phase refers to time shifts between waves of the same or similar frequency

• Measured in Degrees360 = Full Cycle

Green wave is shifted by 360, or a full wave cycle.

Therefore looks just like the original Blue wave.

Building Blocks

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Interfering Waves

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Blue wave andPhase-Shifted Green wave

Add up to Red wave

10

90

180

Interfering Waves

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Blue wave andPhase-Shifted Green wave

Add up to Red wave

10

90

180

Interfering Waves

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Blue wave andPhase-Shifted Green wave

Add up to Red wave

10

90

180

Demo

2 Speakers emitting 329 Hz Sine Waves

Interfering Waves

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Blue wave andPhase-Shifted Green wave

Add up to Red wave

10

90

180

Interfering Waves

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Blue wave andPhase-Shifted Green wave

Add up to Red wave

10

90

180

Interfering Waves

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Blue wave andPhase-Shifted Green wave

Add up to Red wave

10

90

180

Building Blocks

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Beating: Interference in Action

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Beating: Interference in Action

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Higher Frequency

Lower Frequency

Time → e

1

1

12

11

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Higher Frequency

Lower Frequency

1

1

12

11

Beating: Interference in Action

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Higher Frequency

Lower Frequency

Beating: Interference in Action

Demo

329 Hz + 330 Hz gives 1 Hz Beat,

etc.

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Beating: Interference in Action

Another Example:3 Simultaneous Tones:

440 Hz441 Hz443 Hz

Hear complex beat pattern (1Hz, 2 Hz and 3 Hz)

Building Blocks

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The Octave: Doubling the Frequency

• Doubling or Halving the Frequency has special significance in all musical traditions.

• A musical Note and its Octave (i.e. double f ) sound especially good together.

2:1 is the most harmonious ratio

• If a Note with Fundamental Frequency f exists in a musical tradition,

then so does its Octave 2f .

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The Octave: Doubling the Frequency

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0

200

400

600

800

1000

1200

1400

1600

1800

1 1 2 2 3 3 4

Fre

qu

en

cy (H

z) →

200 & 400 Hz Fundamentals + Harmonics

200 Hz

400 Hz 410 Hz 420 Hz

200+

402

200+

410

200+

420

200+

400

402 Hz

These tones have 12 harmonics

200+

403

All the partials (Fundamental and harmonics) of the 400 Hz note were already in the 200 Hz note! So they sound good together.

Nice! Beats! Harsh! Harsher!

The Octave: Remembering It

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2x

Some

-where

The Octave: Remembering It

1/27/20 Sound of Music 1

2x

Some

-where Somewhere Over the Rainbow…

The Octave: Remembering It

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G3-> G4

Course Outline

1. Building Blocks: Some basic concepts

2. Resonance: Building Sounds

3. Hearing and the Ear

4. Musical Scales

5. Musical Instruments

6. Singing and Musical Notation

7. Harmony and Dissonance; Chords

8. Combining the Elements of Music

1/27/20 Sound of Music 1 78