From Noise To Music…

Why does playing the same note give a much different sound?

Reflection and interference are the ingredients needed to make a musical instrument sound the way it does.

Let’s find out in Activity 8!

What Type of Interference Occurs When the Reflected and New Wave Interact?

1. Constructive 2. Destructive

What Type of Interference Occurs When the Reflected and New Wave Interact?

1. Constructive 2. Destructive

Continuous Interference

It’s Standing Still!Standing waves have areas of destructive and

constructive interference.

Nodes - Destructive Antinodes - Constructive

The wave appears to be stationary in space.

How many nodes and antinodes in this standing wave?

5 nodes

4 antinodes

What’s the Frequency?Standing waves are formed at certain frequencies.

The frequency required to make the simplest standing wave is known as

the fundamental frequency.

The other frequencies are known as overtones.

The frequencies of standing waves are also known as harmonic frequencies.

Harmonic Overtone1st Fundamental2nd 1st3rd 2nd4th 3rd

fn = nf1

f1 = fundamental frequency

What’s the Pattern?

L = 12 λ1

L = 22 λ2

L = 32 λ3

f1

f2

f3

L = n2 λn

v = fλ

fn= v2L

n

They Are Not All The Same!The harmonic frequency pattern that we explored is

for instruments with ends that are both fixed.

Let’s explore how the harmonic frequency patterns

look for the winds and woodwind instruments to

finally answer our question:

How Do They Compare?

Fixed

Guitar3 antinodes 4 nodes

Both Open

Flute4 antinodes 3 nodes

One Open

Clarinet3 antinodes 3 nodes

Why are they different?Fixed One Open Both Open

fn= nv2L

fn= nv2L

fn= nv4L

One end open only creates odd harmonics, while both open makes all harmonics.

Why does the water level matter??

Length of air column changes!Less water, longer length,

lower frequency!

Let’s Make Some Music!

1. Get a glass and a metal utensil.

2. Gently clink the glass with the utensil to make a sound.

3. Add water to the glass and clink again.

4. Continue adding water and clinking.

What happens to the sound as you add water?

Why do you think this occurs?

What Happens When You Tap Them?

The less water, the higher the frequency!

What Happens When You Tap Them?

To play the water glasses, you need to vibrate the glass to

vibrate the air to make a sound.

More water, the harder it is for the glass to vibrate.

The vibration of the glass will determine the

frequency of the sound!

The harder it is to vibrate, the lower the frequency.

The mass of the medium impacts the sound that we hear!

What Frequency Do You Hear?

Every object has a natural frequency at which it will vibrate

The natural frequency of an object is based on the physical parameters of the object.

Known as its resonant frequency.

Amount of water Type of Glass

Shape of Glass

Most objects have multiple natural frequencies!

How Does This Happen?

In your groups, determine what needs to be done to make the glass break.

What Do You Need To Break A Glass?

A sound that is at the natural frequency of the object.

A sound at the natural frequency that is loud enough!

Resonance

What’s The Loudest A Human Can Sing?

Smilyana Zaharieva from Bulgaria holds the world record for singing the loudest note.

Held the note at 121 db for 5 seconds!

Why Do Similar Instruments Sound Different?

The sound you hear when a note is played is a combination of the fundamental and harmonic frequencies.

Violin Saxophone

Flute Bassoon

Using a microphone, you can create a graph of frequency and amplitude, known as an FFT graph.

Why Do Similar Instruments Sound Different?

What you hear is dependent on the number of harmonics present and the relative amplitude of those harmonics.

Violin Flute

The size and shape of the instrument will cause these

changes!

Sound Fun Fact!The largest instrument in the world is the

stalactite organ in Virginia.

Other Big Instruments

Other Big Instruments

Other Big Instruments