Perception Test 3

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  1. Source of vibrations?
    the object vibrating
  2. What is the medium?
    the material around the object in which the vibrations are transmitted through
  3. When an object vibrates it...?
    It is going to change the pressure in the medium around it and is going to change the pressure in the waves.
  4. How far do molecules and waves go in the medium?
    Molecules don't go very far but waves go far until they are obstructered by something else
  5. Sound Waves-
    • - travel faster through denser medium(faster through water than air)
    • - Sound Waves we hear are jus fluctuations in air pressure over time
  6. Amplitude
    the magnitude of pressure change. The diff between the highest and lowest pressure areas
  7. Frequency
    • the number of times per second that the pattern of pressure changes, repeats
    • -measured in Hertz=Hz
  8. 1 Hz=
    • 1 cycle per second
    • Cycle is movement movement all the way up and down
  9. Perceptual qualities of Amplitude
    • associated with the perceptual quality of loudness.
    • as amplitude inc. loudness inc.
  10. Perceptual Qualities of Frequency
    • associated with pitch
    • low cycles per second= low pitch
    • high cycles per second= high pitch
  11. Audible Frequencies
    • human hearing uses limited range of frequencies present in the environment.
    • Is similar to visible light
    • We can hear from about 20 to 20,000 Hz
    • Sensitivity to sound frequency is species dependent(dog whistle)
  12. Audible Intensities
    • Very wide range
    • Intensity measured in decibels (dB)
    • Small decibel increase corresponds with large physical range
  13. Sine Wave
    (Simplest kind of Sound Wave)
    • Also known as pure tone
    • The air pressure changes continuously at the same frequency
  14. 2 Characteristics of Sine Wave
    • Period-time taken for one complete cycle
    • There are 360 degrees across one period
    • Phase-relative position of 2 or more sine waves
    • Not very common everyday. Can be found in a tuning fork and hearing tests. Flutes can almost produce sine waves.
  15. Complex Tones
    • Sound wave consisting of more than one sinusoidal component of different frequencies
    • Pressure changes are not the same throughout the whole cycle
  16. All sounds can be describes as combinations of...?
    Sine Waves
  17. Fourier Analysis
    allows us to break down complex tones into their component/relative freaquencies (can be broken down into a high frequency and low frequency tones that when put together equal the complex tone)
  18. Complex Tones..

    a representation of the relative energy or amplitude, present in each frequency that makes up that complex tone.
  19. Most complex tones have a Fundamental Frequency(FO)-
    the lowest frequency component of a complex tone
  20. Harmonic Spectrum
    • Energy at integer multiples of the Fundamental frequency
    • Is typically created by a simple vibrating source such as a guitar string or a sex reed.
  21. In Harmonic Spectrum each frequency is called....?

    The shape of the spectra changes as instruments play the same notes
  22. Timbre
    • Sound quality
    • -Relative energy levels of harmonic components
    • -Different instruments have different timbres
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Perception Test 3
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