The Physical Nature of Sound Flashcards
What is a Sound Wave?
Sound Wave - alterations in pressure which propel themselves through an elastic medium.
*With singing , elastic medium is Air.
Describe the Phase’s of a Sound Wave -
Each wave has -
Compression Phase - Increased pressure
leaving behind…
Rarefaction Phase - Decreased Pressure.
Where does the Fastest & Slowest Speed occur?
- Slowest speed occurs at the Two Extreme Positions
- Fastest speed occurs at the Median of its Oscillation
What are the three distinct Properties of Musical Sound?
Musical Sound has three distinct Properties
- Frequency
- Amplitude
- Timbre
Define Frequency
Frequency = number of vibratory cycles per second - labeled as:
- cps: cycles per second, or
- Hz - Hertz
Define Period
Period = time taken to complete one vibratory cycle
Addendum from the book - period is time not distance
How is a Wave Length calculated?
Wave Length calculated by dividing Speed of Sound (1130 feet or 345 meters per second) by the frequency of the wave.
Describe the relationship between Frequency and Wave Length -
The higher the Frequency, the shorter the Wave Length.
Define Pitch
Pitch - The minds interpretation of Frequency.
Where is the ears maximum Frequency and Amplitude sensitivity?
Ear has its maximum Frequency and Amplitude sensitivity between 50 Hz and 4,000 Hz.
What is Amplitude?
Amplitude - Maximum displacement from a rest position.
*The greater the amplitude, the more Energy Transmitted.
Describe how Instruments, specifically the Human Voice are Transformers -
- 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.
What is Loudness?
Loudness - The ear’s subjective evaluation of a sound waves Amplitude.
Define Sound Intensity
Sound Intensity - Sound Power per unit Area (watts/ m2 or Cm2)
What is Sound Pressure?
Sound Pressure - (measured as SPL)
Local Pressure Deviation as compared with Atmospheric Pressure (caused by sound wave).
Describe Decibels?
Decibels - Ratio of given Intensity (I) to threshold of Hearing (Threshold = 0 decibels).
*Labeled as dB
What advantages do Males have over Females, and Vice Versa, in regards to Amplitude, Vibration and Acoustics?
- 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.
What is Timbre?
Timbre (Tone Quality) - Quality of a musical note, sound or tone that distinguishes different types of sound production.
What is Timbre determined by?
Timbre is determined primarily by:
- Number of Partials
- Distribution of Partials
- Relative Intensity (Strength) of Partials
- Inharmonic Partials (not even multiples of F0)
- Fundamental Tone.
- Total Intensity
What is Damping?
Damping - Time Rate at which Energy is dissipated in a Vibrating body.
What is Interference?
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
What sets singing apart?
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.
Describe the Acoustical Laws regarding Volume -
Volume - The larger the cavity, the Lower the frequency at which it resonates. The Smaller the Cavity, the Higher the frequency.
Describe the Acoustical Laws regarding Size of Aperture -
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.
