Music by Handel

Water Music Suite - Allegro

Pre

ssu

re

Time

1 s

What we already learnt …

Amplitude

Amplitude

E.g.: Frequency = 2 Hz

•Graphical representation of the sound wave: Waveform

•Amplitude

•Frequency (No. of waves per second) =

Speed

Wavelength

Why do a man and a woman sound different?

What distinguishes one sound from another?What distinguishes one sound from another?

Why do a violin and a piano sound different?

Why do a rooster and a monkey sound different?

Goto

Musical Instruments Exploration

•Try out the instruments.

•Complete Section A on your worksheet.

•Pass instrument sets onto next group.

•You’ve got 5 minutes for each sets.

Total 3 sets.

Sound Characteristic 1: Loudness

The loudness of sound is dependent on the amount of energy which is transferred to the medium. It in turn is dependent on the amplitude of vibrations of the object.

Louder sound

Harder you hit the membrane(More energy transfer)

Larger amplitude of vibration

Sound Characteristic 1: Loudness

Compare the waveforms below:

Higher amplitude

!

What determines the loudness of sound?The amplitude of vibration.

Sound Characteristic 1: LoudnessCommon sounds and their estimated loudness:

SourceIntensity

Level# Times

Greater Than TOH

Threshold of Hearing (TOH) 0 dB 100

Rustling Leaves 10 dB 101

Whisper 20 dB 102

Normal Conversation 60 dB 106

Busy Street Traffic 70 dB 107

Vacuum Cleaner 80 dB 108

Large Orchestra 98 dB 109.8

Walkman at Maximum Level 100 dB 1010

Front Rows of Rock Concert 110 dB 1011

Threshold of Ear Pain 130 dB 1013

Military Jet Takeoff 140 dB 1014

Instant Perforation of Eardrum 160 dB 1016

One convenient unit of sound level:

The faintest sound a human ear can hear

is called the

Decibel (dB)

Threshold of Hearing

Sound Characteristic 2: Pitch

Sound waves are caused when a vibrating object introduce vibration into a medium.

Vibrating objects e.g. vocal cords, guitar string & sound board, tines of tuning fork, diaphragm of a radio speaker etc.

Medium e.g. air, water particles etc.

How often the particles of the medium vibrate when a wave passes through the medium is referred to the frequency of a wave.

Sound Characteristic 2: Pitch

Compare the waveforms below:

What determines the pitch of sound?

The frequency of vibration.

Higher frequency

!

Each vibrating object has its own frequency.

Sound Characteristic 2: Pitch

HumanHuman

?

Piano & GuitarPiano & Guitar

Sound Characteristic 3: Quality

Similar musical notes (i.e. same pitch) sounds different on different instruments (e.g. piano and guitar).

These sounds have different quality or timbre.

The quality of the pitch may be due to other weaker frequencies (called overtones), or deliberately mixed (as with a synthesizer).

Sound Characteristic 3: Quality

Compare the waveforms below:

What determines the quality of sound?

The waveform.

What we learnt today …

Soft LoudLoudness

Quality or Timbre

Pitch

depends on the amplitude of vibration

depends on frequency

depends on waveform

Low High

Mixed

Characteristics of sound

Clearer

Some time for reflection…Some time for reflection…

Have a sound Have a sound day!day!Have a sound Have a sound day!day!

A) Laryngeal prominence (Adam's Apple)

B) Larynx (voice box) (vocal cords inside)

C) Trachea (wind pipe)

D) Esophagus (swallowing tube)

As one reaches puberty, the larynx grows for both boys and girls.

Most girls’ larynx however don’t grow as much as boys’.

Larger larynx gives a deeper voice => lower pitch.

Our larynx (vocal box) is just like a wind instrument.Discuss how blowing into a column of air changes pitch when we vary:

The length of the air column

Goto

Shorter column

Longer column

Shorter wavelength Higher frequency

Longer wavelength Lower frequency