♫ resonance ♫ the principle behind the design of musical instruments

♫ ♫ Resonance ♫Resonance ♫

The principle behind the design of The principle behind the design of musical instrumentsmusical instruments

What is What is Resonance? Resonance?

When does it When does it occur?occur?

Applications of ResonanceApplications of Resonance

What is What is Resonance? Resonance?

• Standing WaveStanding Wave• Big AmplitudeBig Amplitude

When does it When does it occur?occur?

Applications of ResonanceApplications of Resonance

What is What is Resonance? Resonance?

• Standing WaveStanding Wave• Big AmplitudeBig Amplitude

When does it When does it occur?occur?

• When the system When the system is being driven at is being driven at its natural its natural frequencyfrequency

Applications of ResonanceApplications of Resonance

Applications of ResonanceApplications of Resonance

Natural Frequency Natural Frequency Driving FrequencyDriving Frequency

What’s the difference?

Applications of ResonanceApplications of Resonance

Natural Frequency Natural Frequency Driving FrequencyDriving Frequency

Fixed StringFixed String

Natural Frequency (n v / 2 L) = Driving Frequency Natural Frequency (n v / 2 L) = Driving Frequency

RESONANCERESONANCE

Natural Frequency Natural Frequency Driving Frequency Driving Frequency

NO RESONANCENO RESONANCE

Resonance: Good or Bad?Resonance: Good or Bad?

GOODGOODMusicMusicElectronics Electronics (sometimes)(sometimes)NMR / MRINMR / MRI

(Nuclear Magnetic (Nuclear Magnetic Resonance – used in Resonance – used in medicine)medicine)

BADBADEarthquakesEarthquakesCar EnginesCar EnginesBuilding vibrations Building vibrations (Civil engineers try to (Civil engineers try to avoid resonance) avoid resonance)

Medieval RiddleMedieval Riddle

From 1511:From 1511:

““What thing is it, the less it is, the more it is What thing is it, the less it is, the more it is dread?”dread?”

BAD RESONANCEBAD RESONANCE

Lessons from the Lessons from the Prussian ArmyPrussian Army

Modern disasters Modern disasters of resonance:of resonance:

1) Collapse of 1) Collapse of suspension bridge suspension bridge in France in 1850in France in 1850

2) Washington State: 2) Washington State: “Galloping Gertie”“Galloping Gertie”

Flame Tube Flame Tube AKA Rubens TubeAKA Rubens Tube

1.1. Fill pipe with propane or other flammable Fill pipe with propane or other flammable gasgas

2.2. Turn on SpeakerTurn on Speaker

3.3. Set on FireSet on Fire

Bridgewater Bridgewater

College College

Flame TubeFlame Tube

Dec 2011Dec 2011

Exciting Resonance Exciting Resonance ApplicationsApplications

Breaking Glass with your voiceBreaking Glass with your voice

Vocal Coach Jaime Vendera Shatters Glass # 85

Youtube comment: “You know he's wearing glasses because one of the 84 previous glasses stuck him in the eye.”

MICROWAVE OVEN MICROWAVE OVEN HYPOTHESIS HYPOTHESIS

Resonance or Not?Resonance or Not?

Microwave Oven: 1) Microwaves2) Water-based food (with some natural frequency)

RESONANCE IN MUSICRESONANCE IN MUSICResonance Cavities in string instrumentsResonance Cavities in string instrumentsDoes every violin need to look like this:Does every violin need to look like this:

Stradivarius

RESONANCE IN MUSICRESONANCE IN MUSIC

Electric violins & guitars don’t need to resonateElectric violins & guitars don’t need to resonate

Therefore, they can have funny shapesTherefore, they can have funny shapes

IS THERE SOMETHING SPECIAL IS THERE SOMETHING SPECIAL ABOUT STRADIVARIUS VIOLINS?ABOUT STRADIVARIUS VIOLINS?

DigressionDigression

The Great Stradivarius Debate:

Truth or Hype?

DigressionDigression

The Great Stradivarius Debate

HOLOGRAPHIC HOLOGRAPHIC INTERFEROMETRYINTERFEROMETRY

Analyzing vibrations of string instrument Analyzing vibrations of string instrument bodiesbodies

BASSBASS

(TWO COLUMNS (TWO COLUMNS FROM LOW TO FROM LOW TO HIGH FREQUENCY)HIGH FREQUENCY)

RESONATING SAND RESONATING SAND VIDEOVIDEO

Analyzing vibrations of string instrument bodies

WHAT DRIVES THE INSTRUMENT?WHAT DRIVES THE INSTRUMENT?

String instruments (eg, Violin) String instruments (eg, Violin)

Wind instrumentsWind instruments

Brass InstrumentsBrass Instruments

WHAT DRIVES THE INSTRUMENT?WHAT DRIVES THE INSTRUMENT?

Violin – BowViolin – Bow

Wind instruments Wind instruments – Reed– Reed

Brass Instruments – lips must vibrateBrass Instruments – lips must vibrate

How does the reed (or your lips) “know” which How does the reed (or your lips) “know” which frequency to vibrate at?frequency to vibrate at?

SUMMARYSUMMARY

• What must be true for resonance to occur?What must be true for resonance to occur?

• How do you know when it is occuring?How do you know when it is occuring?