Chapter 21

1
Chapter 21 The Nature of Sound

• Section 4 Sound Quality
• pp. 618 - 621

2
TERMS TO LEARN

• Sound quality the result of several pitches
  blending together through interference
• Noise an undesired sound

3
WHAT IS SOUND QUALITY?

• If the same note is played with the same loudness
  on two different instruments, could you tell the
  instruments apart without looking?
• Yes, you could because the sounds instruments
  produce are not the same.

4
WHAT IS SOUND QUALITY?

• The notes sound different because each instrument
  produces several different pitches the
  fundamental and several overtones.
• The result of several pitches blending together
  through interference is called sound quality.

5
SOUND QUALITY OF INSTRUMENTS

• The difference in sound quality of instruments
  comes from structural differences in the
  instruments (what the instrument is made of and
  how the instrument is made).

6
3 MAIN FAMILIES OF INSTRUMENTS

• String instruments
• Wind instruments
• Percussion instruments

7
STRING INSTRUMENTS
8
STRING INSTRUMENTS

• How they make sounds They produce sound when
  their strings vibrate after being plucked or
  bowed.
• See Figure 2 on p. 619 for comparison of cello
  and electric guitar.

9
WIND INSTRUMENTS

• 2 types of wind instruments
• Woodwind
• Brass

10
WOODWINDS
11
BRASS
12
WIND INSTRUMENTS

• How wind instruments produce sound a vibration
  is created at one end of its air column, and then
  the vibration creates standing waves in the air
  column.
• See Figure 3 on p. 620.

13
PERCUSSION
14
PERCUSSION

• How they make sounds They produce sound when
  they are struck

15
MUSIC OR NOISE?

• Noise is any undesired sound that includes a
  random mix of pitches.
• Music is sound that has a pleasing quality, a
  definite repeated timing called rhythm and an
  identifiable pitch.

16
NOISE POLLUTION

• When noise reaches a level that causes pain or
  damages the body it is called noise pollution.
• Noise pollution can damage the inner ear, causing
  permanent hearing loss.
• Noise pollution can contribute to sleeplessness,
  high blood pressure and stress.

17
WHITE NOISE

• This is an equal mixture of all frequencies (like
  white light is a mixture of all colors).
• White noise machines are used to calm people and
  help make them sleep.