The Physical Nature of Sound

Question 1

What is a Sound Wave?

Answer 1

Sound Wave - alterations in pressure which propel themselves through an elastic medium.
*With singing , elastic medium is Air.

Question 2

Describe the Phase’s of a Sound Wave -

Answer 2

Each wave has -
Compression Phase - Increased pressure
leaving behind…
Rarefaction Phase - Decreased Pressure.

Question 3

Where does the Fastest & Slowest Speed occur?

Answer 3

• Slowest speed occurs at the Two Extreme Positions

- Fastest speed occurs at the Median of its Oscillation

Question 4

What are the three distinct Properties of Musical Sound?

Answer 4

Musical Sound has three distinct Properties

1. Frequency
2. Amplitude
3. Timbre

Question 5

Define Frequency

Answer 5

Frequency = number of vibratory cycles per second - labeled as:

• cps: cycles per second, or
• Hz - Hertz

Question 6

Define Period

Answer 6

Period = time taken to complete one vibratory cycle

Addendum from the book - period is time not distance

Question 7

How is a Wave Length calculated?

Answer 7

Wave Length calculated by dividing Speed of Sound (1130 feet or 345 meters per second) by the frequency of the wave.

Question 8

Describe the relationship between Frequency and Wave Length -

Answer 8

The higher the Frequency, the shorter the Wave Length.

Question 9

Define Pitch

Answer 9

Pitch - The minds interpretation of Frequency.

Question 10

Where is the ears maximum Frequency and Amplitude sensitivity?

Answer 10

Ear has its maximum Frequency and Amplitude sensitivity between 50 Hz and 4,000 Hz.

Question 11

What is Amplitude?

Answer 11

Amplitude - Maximum displacement from a rest position.

*The greater the amplitude, the more Energy Transmitted.

Question 12

Describe how Instruments, specifically the Human Voice are Transformers -

Answer 12

• Musical Instruments are “Transformers”.
  i. e. They transform Energy into Audible Sound.
• Human Voice is one of the most efficient Transformers
• Although it only converts One Percent of the Energy into Audible Sound.

Question 13

What is Loudness?

Answer 13

Loudness - The ear’s subjective evaluation of a sound waves Amplitude.

Question 14

Define Sound Intensity

Answer 14

Sound Intensity - Sound Power per unit Area (watts/ m2 or Cm2)

Question 15

What is Sound Pressure?

Answer 15

Sound Pressure - (measured as SPL)

Local Pressure Deviation as compared with Atmospheric Pressure (caused by sound wave).

Question 16

Describe Decibels?

Answer 16

Decibels - Ratio of given Intensity (I) to threshold of Hearing (Threshold = 0 decibels).
*Labeled as dB

Question 17

What advantages do Males have over Females, and Vice Versa, in regards to Amplitude, Vibration and Acoustics?

Answer 17

• Male vocal folds are Longer, therefore drive more air which creates a larger Amplitude of Vibration (Titze)
• Females singer Higher Frequencies giving them an Acoustical Advantage.

Question 18

What is Timbre?

Answer 18

Timbre (Tone Quality) - Quality of a musical note, sound or tone that distinguishes different types of sound production.

Question 19

What is Timbre determined by?

Answer 19

Timbre is determined primarily by:

1. Number of Partials
2. Distribution of Partials
3. Relative Intensity (Strength) of Partials
4. Inharmonic Partials (not even multiples of F0)
5. Fundamental Tone.
6. Total Intensity

Question 20

What is Damping?

Answer 20

Damping - Time Rate at which Energy is dissipated in a Vibrating body.

Question 21

What is Interference?

Answer 21

Interference - Effect produced by a Superposition of two or more systems of waves in which these waves reinforce, Neutralize, or in other ways Interfere with each other.

• Constructive - In Phase
• Destructive - Out of Phase

Question 22

What sets singing apart?

Answer 22

What sets singing apart…….

• The sound wave produced is a saw-tooth type containing the fundamental and its harmonics.
• The harmonic output (sound wave) of the vocal cords can be varied to some extent.
• The F0 of the wave can be varied over at least two octaves.
• Vocal cavities posses several different discrete or distinct resonant frequencies which can be varied i.e. , certain overtones can be accentuated.

Question 23

Describe the Acoustical Laws regarding Volume -

Answer 23

Volume - The larger the cavity, the Lower the frequency at which it resonates. The Smaller the Cavity, the Higher the frequency.

Question 24

Describe the Acoustical Laws regarding Size of Aperture -

Answer 24

Size of Aperture - the Longer and Narrower the neck of the opening, the Lower the frequency to which the cavity responds. The Wider and Flatter the neck, the Higher the frequency to which it responds.

Question 25

Describe the Acoustical Laws regarding Texture of the Walls -

Answer 25

Texture of the Walls - The Softer the walls, the more the Lower Harmonics are emphasized. The Harder the wall, the more the Higher Harmonics are emphasized.

Question 26

Describe the Acoustical Laws regarding Conductivity Factor

Answer 26

Conductivity Factor - Coupling of the Resonators can enhance the Acoustic Information generated at the Source (Vocal Folds).