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2011-11-21 13:32:43
Hearing Env

chapter 10
Show Answers:

  1. Monaural cue for distance and direction:
    Dopplar Shift-
    • The changein pitch of a sound heard when the source and observer are in relative motion to each other
    • As the observer and sound source come together, the perceived pitch is higher
    • As the observer and sound source move apart, the perceived pitch is lower
  2. Binaural cue for distance/direction
    • 1. Interaural time difference
    • 2. Interaural level difference
  3. Interaural time difference:
    • A sound will arrive at each ear at slightly different times
    • We have cells that fire for specific time differences between ears.
    • They are coding for direction
  4. Echo and Precedence Effect
    • Echo: repetition of a sound due to sound bouncing off ofsurfaces.
    • Thats why we sound better singing in the shower
  5. Why dont we perceive all of these echoes?
    • Auditory system considers the first version the most important and suppresses other versions that arrive up to 30 min. later
    • Called the precedence effect
  6. Internaural level difference (intensity difference)
    • Most sounds are louder in one ear than the other
    • Works for sounds greater than 1000Hz because of sound shadow
  7. Cone of Confusion:
    positions in space where all sounds produce the same ITDs and ILDs
  8. Solution to Cone of confusion:
    moving our head creates ILD/ITD differences
  9. Pinna Cues
    • Sounds approaching pinna from the front are reflected into the ear canal differently than sounds approaching from other direcctions
    • Creates Head Related Transfer Functions (HRTF)
    • Gives us location information
  10. Bats-
    Experts at sound localization
  11. Echolocation:
    • using echoes of self produced sounds from objects to learn about environment
    • Compare emitted sound with sound that bounces back to locate and identify objects
  12. Head related transfer function:
    A function that describes how the pinna, ear canal, head, and torso change the intensity of sounds with different frequencies that arrive at each ear from different locations in space
  13. Inverse square law
    principle stating that as distance from a source increases, intensity decreases faster such that decrease in intensity is the distance squared
  14. Attack:
    The part of a sound during which amplitude increases (onset)
  15. Decay:
    The part of a sound during which amplitude decreases (offset)
  16. Azimuth
    the angle of a sound source on the horizontal plane relative to a point in the center of the head between the ears