Unit 1.2

Question 1

Acoustics of Music

Answer 1

• we recognize noise vs. music very easily
• acoustics = sound of science (production/transmission/reception)
• musical acoustics = mechanisms of sound production by musical instruments, effects of room design and human perception of sound as music

Question 2

Physical Characteristics of Sound Waves

Answer 2

• air matters (sound = moving air particles)
• sound propagates through air, forms a pressure wave

Question 3

Air pressure and sine waves

Answer 3

Sound wave (acoustic pressure wave)
- formed from pattern of air compression and expansion/rarefaction
- travels from source of disturbance to our ears
Sound waves are longitudinal

Question 4

Properties of Sine Waves (2)

Answer 4

• frequency (cycles per second): pitch
• amplitude: loudness

Question 5

Complex waves

Answer 5

• pure tones (single sine wave = very rare)
• most sounds are complex: not sinusoidal or a single frequency
• Fourier transform

Question 6

Fourier transform

Answer 6

complex waves can be broken down into a series of simple sine waves

Question 7

What are overtones?

Answer 7

• a complex tone has multiple frequencies
• fundamental freq = lowest freq of sound
• overtones = all freq in a sound higher than the fundamental freq

Question 8

Harmonics

Answer 8

• harmonic overtones: integer multiple of the fund freq
• harmonic overtones convey a clear pitch
• anharmonic complex tones: overtones are NOT integer ratios

Question 9

Power spectrum (x and y axis)

Answer 9

x - freq
y - amplitude

Question 10

Sonogram (x and y axis)

Answer 10

x - time
y - frequency

Question 11

Waveform

Answer 11

x - time
y - amplitude